Methods and systems of mesh configuration of radio frequency identification (rfid) communication

ABSTRACT

Various embodiments illustrated herein disclose a radio-frequency identification (RFID) reader having a first RFID tag having a first antenna element operating at a first transmit power. The first RFID tag receives, in a first time interval, a first interrogation command from a first RFID reader through the first antenna element. The first RFID tag transmits, in the first time interval, a first response signal to the first RFID reader. The RFID reader comprises a second antenna element that operates at a second transmit power and a processor communicatively coupled to the second antenna element. The processor transmits, in the first time interval, a second interrogation command to one or more second RFID tags through the second antenna element. The first RFID tag transmits, in a second time interval, a third interrogation command to a first RFID tag of a second RFID reader through the first antenna element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority pursuant to 35 U.S.C. 119(a) to IndiaPatent Application No. 202111022397, filed May 19, 2021, whichapplication is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Example embodiments of the present disclosure relate generally toradio-frequency identification (RFID) communication and, moreparticularly, to methods and systems of mesh configuration of RFIDcommunication.

BACKGROUND

A RFID system may be at least used for asset tracking, where one or moreRFID tags may be placed on one or more assets that are to be tracked bya large number of RFID readers covering large geographically distributedcritical zones corresponding to a work environment such as, a hospital,a warehouse, a store, etc. For example, the RFID system may includemultiple RFID readers that may be positioned at fixed locations in thework environment (where the one or more assets are to be tracked). Thesemultiple RFID readers spread about a vast work environment are typicallyconnected to a backend server using RF cables.

BRIEF SUMMARY

Various embodiments illustrated herein disclose a radio-frequencyidentification (RFID) reader. The RFID reader comprises a first RFID tagcomprising a first antenna element. The first antenna element isconfigured to operate at a first transmit power. The first RFID tagreceives, in a first time interval, a first interrogation command from afirst RFID reader through the first antenna element. In response toreceiving the first interrogation command, the first RFID tag transmits,in the first time interval, a first response signal to the first RFIDreader. The RFID reader comprises a second antenna element that operatesat a second transmit power. The second transmit power of the secondantenna element is below the first transmit power of the first antennaelement. The RFID reader comprises a processor communicatively coupledto the second antenna element. The processor transmits, in the firsttime interval, a second interrogation command to one or more second RFIDtags through the second antenna element. The processor receives a secondresponse signal from the one or more second RFID tags in the first timeinterval through the second antenna element, in response to transmittingthe second interrogation command. The first RFID tag transmits, in asecond time interval, a third interrogation command to a first RFID tagof a second RFID reader through the first antenna element operating atthe first transmit power. The second time interval occurs subsequent tothe first time interval. The first RFID tag of the RFID reader receives,in the second time interval, a third response signal from the secondRFID reader.

Various embodiments illustrated herein disclose a method that includesreceiving, by a first RFID tag of an RFID reader, through a firstantenna element of the RFID reader in a first time interval, a firstinterrogation command from a first RFID reader. The first antennaelement operates at a first transmit power. The method includestransmitting, by the first RFID tag, in the first time interval, a firstresponse signal to the first RFID reader, in response to receiving thefirst interrogation command. The method includes transmitting, by aprocessor of the RFID reader, in the first time interval, a secondinterrogation command to one or more second RFID tags through a secondantenna element of the RFID reader. The second antenna element operatesat a second transmit power that is below the first transmit power of thefirst antenna element. The method further includes receiving, by theprocessor of the RFID reader, a second response signal from the one ormore second RFID tags in the first time interval through the secondantenna element, in response to transmitting the second interrogationcommand. The method further includes transmitting, by the first RFID tagof the RFID reader, in a second time interval, a third interrogationcommand to a first RFID tag of a second RFID reader through the firstantenna element operating at the first transmit power. The second timeinterval occurs subsequent to the first time interval. The methodfurther includes receiving, by the first RFID tag, in the second timeinterval, a third response signal from the second RFID reader.

The foregoing illustrative summary, as well as other exemplaryobjectives and/or advantages of the disclosure, and the manner in whichthe same may be accomplished, may be further explained in the followingdetailed description and its accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of the illustrative embodiments can be read inconjunction with the accompanying figures. It will be appreciated thatfor simplicity and clarity of illustration, elements illustrated in thefigures have not necessarily been drawn to scale. For example, thedimensions of some of the elements are exaggerated relative to otherelements. Embodiments incorporating teachings of the present disclosureare shown and described with respect to the figures presented herein, inwhich:

FIG. 1 illustrates a block diagram of a system environment, according toone or more embodiments described herein;

FIG. 2 illustrates a block diagram of an example master RFID reader,according to one or more embodiments described herein;

FIG. 3 illustrates a block diagram of an example slave RFID reader,according to one or more embodiments described herein;

FIG. 4 illustrates a block diagram of a noise cancellation unit,according to one or more embodiments described herein;

FIG. 5 illustrates an example timing diagram of operation of differentRFID readers in a dense reader mode (DRM), according to one or moreembodiments described herein;

FIG. 6 illustrates an example timing diagram of transmission ofinterrogation commands by different RFID readers, according to one ormore embodiments described herein;

FIG. 7 illustrates a flowchart to operate an RFID reader, according toone or more embodiments described herein;

FIG. 8 illustrates a flowchart to operate the slave RFID reader in adense reader mode (DRM), according to one or more embodiments describedherein;

FIG. 9 illustrates a flowchart to operate the master RFID reader in thedense reader mode (DRM), according to one or more embodiments describedherein;

FIG. 10 illustrates a schematic diagram of TDMA slots defined by theRFID reader, according to one or more embodiments described herein;

FIG. 11 illustrates a flowchart of a method for operating the RFIDreader, according to one or more embodiments illustrated herein;

FIG. 12 illustrates a flowchart of a method for operating the RFIDreader, according to one or more embodiments illustrated herein;

FIG. 13 illustrates another flowchart of a method for operating thefirst RFID reader, according to one or more embodiments illustratedherein;

FIG. 14 illustrates a flowchart of a method for operating the RFIDreader in the emergency mode, according to one or more embodimentsillustrated herein;

FIG. 15 illustrates an example scenario depicting the communicationamongst the first RFID reader, the RFID reader, and the one or moresecond RFID readers, according to one or more embodiments illustratedherein; and

FIG. 16 illustrates an example scenario depicting the communicationamongst the first RFID reader, the RFID reader, and the one or moresecond RFID readers, during the hazardous scenario, according to one ormore embodiments illustrated herein.

DETAILED DESCRIPTION OF THE INVENTION

Some embodiments of the present disclosure will now be described morefully hereinafter with reference to the accompanying drawings, in whichsome, but not all embodiments of the disclosure are shown. Indeed, thesedisclosures may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will satisfy applicablelegal requirements. Like numbers refer to like elements throughout.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open sense,that is as “including, but not limited to.”

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.Furthermore, one or more particular features, structures, orcharacteristics from one or more embodiments may be combined in anysuitable manner in one or more other embodiments.

The word “example” or “exemplary” is used herein to mean “serving as anexample, instance, or illustration.” Any implementation described hereinas “exemplary” is not necessarily to be construed as preferred oradvantageous over other implementations.

If the specification states a component or feature “may,” “can,”“could,” “should,” “would,” “preferably,” “possibly,” “typically,”“optionally,” “for example,” “often,” or “might” (or other suchlanguage) be included or have a characteristic, that a specificcomponent or feature is not required to be included or to have thecharacteristic. Such component or feature may be optionally included insome embodiments, or it may be excluded.

The term “electronically coupled,” “electronically coupling,”“electronically couple,” “in communication with,” “in electroniccommunication with,” “communicatively coupled”, or “connected” in thepresent disclosure refers to two or more components being connected(directly or indirectly) through wired means (for example but notlimited to, system bus, wired Ethernet) and/or wireless means (forexample but not limited to, Wi-Fi, Bluetooth, ZigBee), such that dataand/or information may be transmitted to and/or received from thesecomponents.

The term “antenna element” is used herein to correspond to a device oran apparatus (for example, an active element) that may be configured togenerate radio frequency (RF) signals when a voltage signal is appliedat the antenna element. For example, the antenna element may beconfigured to generate RF signal in a high frequency (HF) band or a lowfrequency (LF) band. Additionally, or alternatively, the antenna elementmay generate the RF signal in the ultra-high frequency (UHF) band.Additionally, or alternatively, the antenna element may generate the RFsignal in other frequency band(s). In some examples, the antenna elementmay further comprise a matching circuit that, for example, iselectronically coupled to the active element to generate the RF signals.

The term “radio frequency identification (RFID) tag” is used herein tocorrespond to an article, a device, or an apparatus that may comprise anintegrated circuit (IC), an antenna element, and/or a substrate. In anexample embodiment, the antenna element and the IC may be fabricated onthe substrate. In an example embodiment, the IC may be communicativelycoupled to the antenna element through an interconnect on the substrate.In an example embodiment, the integrated circuit in the RFID tag may beconfigured to store encoded information or encoded data. In someexamples, the RFID tag may be configured to operate in one or more RFfrequency bands such as, but not limited to, 3 MHz-30 MHz (the HF band)and/or 860 MHz-960 MHz (the UHF band). In some example embodiments, theRFID tag may have a dedicated power source that may enable the RFID tagto communicate with one or more components. Such RFID tags are referredto as active RFID tags. In alternative example embodiments, the RFID tagmay not have a dedicated power source. Such RFID tags are referred to aspassive RFID tags. In such embodiments, the RFID tag may have a powercoupler that is capable of inducing electrical charge when the RFID tagis brought in an RF field. The induced electrical charge may thereafterbe used to power the RFID tag itself.

A RFID system may include one or more RFID readers. The one or more RFIDreaders may be configured to read one or more RFID tags (placed on oneor more assets) either continuously or periodically. Further, the one ormore RFID readers may be configured to transmit data, obtained from theone or more RFID tags, to a central server periodically. To facilitatethe transmission of the data to the central server, the one or more RFIDreaders may be communicatively coupled to the central server through abackbone network such as, but not limited to, a wireless network, anEthernet network, and/or the like.

The UHF RFID technology is typically used as a cost effective and secureoption for asset tracking in different environments, such as, hospitals,hotels, warehouses, etc., as compared to other conventional assettracking technologies using, for example, Bluetooth, Wi-Fi, etc. Aconventional RFID reader with a 30 dbm output RF power can read an RFIDtag within a range of about 7 meters to 10 meters distance. Such RFIDreaders are connected to a backend server via power over ethernet(POE)/Wi-fi connectivity. Typically, commercial RFID readers areequipped with 1-4 RF ports which can be used to connect externalantennas using an RF Cable. Hence, multiple RFID readers are required tocover geographically distributed critical zones of an environment suchas a hospital. However, since RF cables are usually costly and theirlosses increase/meter, the effective radiated power becomes, therebyattributing to low tag read distances. Further, the solution deploymentcost also increases considering high cost of UHF RFID readers, antenna,RF cables, etc.

Systems and methods described herein disclose an RFID system that mayinclude one or more RFID readers. In an embodiment, the one or more RFIDreaders may be configured to transmit data, obtained from one or moreRFID tags (placed on one or more assets), to the central server via amaster RFID reader communicatively coupled to the central server via anetwork. In an embodiment, the master RFID reader and the one or moreRFID readers (slave RFID readers) are configured in a mesh topology toallow transmission of the data to the central server. In an embodiment,the RFID system may comprise an RFID reader at one level of the meshtopology that is coupled to a first RFID reader and a second RFID readerat a preceding level and a subsequent level of the mesh topology,respectively. The systems and methods described herein allow theconventional RFID system to be re-architected in the mesh topology suchthat, the connection of one RFID reader to another RFID reader makes theRFID system more expandable in the form of a mesh as well aseconomically cheap to deploy. As part of this architecture, a masterRFID reader may communicate to many mesh RFID readers (slave readers)using the same RFID Tag protocol like EPC Gen2 Air interface protocol inthe mesh topology.

In some examples, the first RFID reader may correspond to a master RFIDreader that may comprise a communication module. In some examples, thecommunication module in the first RFID reader may be battery powered andmay be capable of communicating with the central server. Thecommunication module may utilize one or more communication protocols,such as, but not limited to, a Wireless Area Network (WAN), a Local AreaNetwork (LAN), and/or a Metropolitan Area Network (MAN), for example,ethernet, 2G, 3G, 4G, 5G, Wireless Fidelity (Wi-Fi) network, WiMAX,ZigBee, Bluetooth, and/or the like to communicate with the centralserver. In some other examples, the first RFID reader may correspond toa slave RFID reader that may comprise a first RFID tag and an RFIDreader unit. In an embodiment, the first RFID tag may comprise a firstantenna element and the RFID reader unit may comprise a second antennaelement. In an embodiment, the first RFID tag of the first RFID readermay communicate with one or more RFID readers via the first antennaelement and the RFID reader unit may communicate with one or more secondRFID tags, for example, placed on one or more assets, via the secondantenna element. In an embodiment, the RFID reader unit may beconfigured to store data, received from the one or more second RFID tagsin a memory unit of the first RFID reader, which the first RFID tag ofthe first RFID reader may communicate with the one or more RFID readersof the mesh topology via the first antenna element of the first RFIDreader.

In some examples, the second RFID reader may correspond to a slave RFIDreader that may comprise a first RFID tag and an RFID reader unit. In anembodiment, the first RFID tag may comprise a first antenna element andthe RFID reader unit may comprise a second antenna element. In anembodiment, the first RFID tag of the second RFID reader may communicatewith one or more RFID readers of the mesh topology via the first antennaelement of the first RFID tag. The second RFID reader may be configuredto utilize the RFID reader unit to, periodically or continuously,interrogate one or more second RFID tags (installed on one or moreassets). Further, the RFID reader unit may be configured to store data,received from the one or more second RFID tags (in response to theinterrogation command) in a memory unit of the second RFID reader, whichthe first RFID tag of the second RFID reader may communicate with theone or more RFID readers of the mesh topology via the first antennaelement of the second RFID reader.

In some examples, the first RFID reader (in the preceding level of themesh topology with respect to the RFID reader) may be configured to,periodically or continuously, interrogate the first RFID tag in the RFIDreader. In this example embodiment, the first RFID reader corresponds tothe master RFID reader that is coupled to the central server via thenetwork. Upon receiving the interrogation command, the first RFID tagmay be configured to access the memory unit of the RFID reader toretrieve the data (received from the one or more second RFID tags in thevicinity of the RFID reader), and/or may be configured to transmit thedata to the first RFID reader. Upon receiving the data from the RFIDreader, the first RFID reader may be configured to transmit the data tothe central server by utilizing the battery powered communication moduleof the first RFID reader.

In some examples, the data may be shared between the first RFID reader(at the preceding level of the mesh topology with respect to the RFIDreader), the RFID reader, and the second RFID reader (at the subsequentlevel of the mesh topology with respect to the RFID reader) inaccordance with one or more RFID communication protocols. As such,example systems and methods do not rely on the backbone network tocommunicate the data between the first RFID reader, the RFID reader, andthe second RFID reader. For example, in scenarios of a power outage, thefirst RFID reader may continue to operate on the battery power. Further,the first RFID reader may be able to interrogate the first RFID tag inthe RFID reader during power outage, as the first RFID tag may bepowered either through a battery in the first RFID tag (i.e., the firstRFID tag is an active RFID tag) or through the RF signals transmitted bythe first RFID reader (i.e., the first RFID tag is a passive tag).Accordingly, the loss of data during such scenarios may be avoided.Further, in environments where Wi-Fi coverage is lacking, the data fromthe RFID tags of the RFID readers at different levels of the meshtopology are transmitted through the RFID system disclosed herein.Examples of the disclosed embodiments may reduce overall cost ofimplementing the RFID system (for example, by reducing the reliance onthe backbone network).

FIG. 1 illustrates a block diagram of a system environment 100 accordingto one or more embodiments described herein. In an embodiment, thesystem environment 100 illustrated in FIG. 1 depicts a mesh topology ofRFID readers. In an example embodiment, the system environment 100 mayinclude a first RFID reader 102, one or more RFID readers 104, 124 (at alevel subsequent to the level of the first RFID reader 102 in the meshtopology), one or more second RFID readers 134, 136, 138, 140 and (at alevel subsequent to the level of the one or more RFID readers 104, 124in the mesh topology), and a central server 106. In an embodiment, thefirst RFID reader 102 may be communicatively coupled to the centralserver 106 through a network 108. In this embodiment, the first RFIDreader 102 corresponds to a master RFID reader of the mesh topology. Inan embodiment, the master RFID reader may provide a tag read range ofabout 7 meters to 8 meters. In some other embodiments, the first RFIDreader 102 may be communicatively coupled to one or more RFID readers104, 124 in the mesh topology. In such an embodiment, the first RFIDreader 102 and the one or more RFID readers 104, 124 correspond to slaveRFID readers of the mesh topology. In some examples, each of the RFIDreaders 104, 124 and the second RFID readers may include a first RFIDtag. For example, the RFID reader 104 comprises the first RFID tag 110,the second RFID reader 134 comprises the first RFID tag 126, etc. Insome examples, the system environment 100 may include one or more secondRFID tags (for example, 112, 122, 132, 142, 144, 146, 148, etc.). In anembodiment, the second RFID tags may be positioned on, for example butnot limited to, one or more assets to be tracked by a respective RFIDreader in the vicinity of the second RFID tags. In an embodiment, thesecond RFID tags are read by one or more RFID readers in the vicinity ofthe respective second RFID tags. For example, the second RFID tags 112are read by the first RFID reader 102, the second RFID tags 122 are readby the RFID reader 104, the second RFID tags 142 are read by the secondRFID reader 134, etc. In an example embodiment, the second RFID tags 122may be similar to the first RFID tag 110. In some examples, theembodiments applicable on the first RFID tag 110 may also be applicableon the second RFID tags 122.

In an example embodiment, the RFID reader 104 may include suitable logicand/or circuitry that may enable the RFID reader 104 to respond to aninterrogation command from the first RFID reader 102, details of whichare further described in FIG. 7. For example, the first RFID reader 102may transmit a first interrogation command to the first RFID tag 110 ofthe RFID reader 104 in a first time interval. The first RFID tag 110 mayrespond to the first interrogation command with a first response signal,in the first time interval. In another example embodiment, the RFIDreader 104 may include suitable logic and/or circuitry that may enablethe RFID reader 104 to interrogate the second RFID tags 122, as well asthe first RFID tag 126 in the second RFID reader 134, details of whichare further described in FIG. 7. For example, the RFID reader 104 maytransmit a second interrogation command and a third interrogationcommand to the second RFID tags 122 in the vicinity of the RFID reader104 and the first RFID tag 126 of the second RFID reader 134,respectively. In an embodiment, the RFID reader 104 transmits the secondinterrogation command to the second RFID tags 122 in the first timeinterval via a second antenna element 118 of the RFID reader 104operating at a second transmit power, and transmits the thirdinterrogation command to the first RFID tag 126 of the second RFIDreader 134 in a second time interval via a first antenna element 120 ofthe first RFID tag 110 of the RFID reader 104 operating at a firsttransmit power. In some examples, the first RFID reader 102 may transmitthe first interrogation command and the RFID reader 104 may transmit thesecond interrogation command and the third interrogation command overone or more frequency bands, such as but not limited to, the HF bandand/or the UHF band. Additionally, or alternatively, the first RFIDreader 102 and/or the RFID reader 104 may utilize one or more modulationtechniques, such as but not limited to, Amplitude Shift keying (ASK) andPhase Jitter Modulation (PJM), to transmit the first interrogationcommand, the second interrogation command, and/or the thirdinterrogation command on the one or more frequency bands. The RF signal,over which the first interrogation command is transmitted to the firstRFID tag 110 of the RFID reader 104, is hereinafter referred to as afirst signal. The RF signal, over which the second interrogation commandis transmitted to the second RFID tags 122, is hereinafter referred toas a second signal. The RF signal, over which the third interrogationcommand is transmitted to the first RFID tag 126 of the second RFIDreader 134, is hereinafter referred to as a second signal.

In response to the first interrogation command, the first RFID reader102 may receive a first response signal from the first RFID tag 110 ofthe RFID reader 104, details of which are further described in FIG. 6.In response to the second interrogation command and the thirdinterrogation command, the RFID reader 104 may receive a second responsesignal and/or a third response signal from the second RFID tags 122 inthe vicinity of the RFID reader 104 and the first RFID tag 126 of thesecond RFID reader 134, respectively, details of which are furtherdescribed in FIG. 7. In an example embodiment, the first responsesignal, the second response signal, and the third response signal mayinclude first data, second data, and third data, respectively. In anembodiment, the first RFID reader 102 may be further configured totransmit the first data, the second data, and/or the third data to thecentral server 106 over the network 108.

In an example embodiment, the first RFID reader 102 may comprise a firstantenna element 114 that may be configured to facilitate transmission ofthe first interrogation command (through the first signal) and receptionof the first data (through the first response signal) from the firstRFID tag 110 of the RFID reader 104. In an example embodiment, the firstantenna element 114 corresponds to an active element that may beconfigured to generate RF signals (e.g., the first signal) when avoltage signal is applied at the first antenna element 114. For example,the first antenna element 114 may be configured to generate the firstsignal in HF band and/or UHF band. Some examples of the first antennaelement 114 may include, but are not limited to, an omnidirectionalantenna, a holographic antenna, a multiple input multiple output MIMOantenna, and/or the like. In some examples, the first antenna element114 may be coupled to a matching circuit (not shown) that may enable thefirst antenna element 114 to generate the first signal. Additionally, oralternatively, the matching circuit may include one or more phaseshifters (not shown) that may allow the first antenna element 114 togenerate one or more beams in one or more directions (hereinafterreferred to as beamforming). Such beamforming of the first signal mayallow the first RFID reader 102 to direct the first signal to aparticular location where the RFID reader 104 may be positioned.

Additionally or alternatively, the first RFID reader 102 may comprise asecond antenna element 116 that may be configured to facilitatetransmission of a second interrogation command (over the second signal)and reception of the second data (via the second response signal) fromthe second RFID tags 112 in the vicinity of the first RFID reader 102.In some examples, the second antenna element 116 may be structurallysimilar to the first antenna element 114. In some examples, theembodiments applicable on the first antenna element 114 may alsoapplicable on the second antenna element 116. Further, in some examples,the first antenna element 114 may be spaced apart from the secondantenna element 116. In some examples, the second antenna element 116may be configured to direct the second signal in a first predetermineddirection. As such, the first RFID reader 102 may scan the second RFIDtags 112 positioned or transiting through a location where the secondsignal is being directed by the second antenna element 116. In variousexamples, the first antenna element 114 and the second antenna element116 may have various configurations. For example, the first antennaelement 114 and/or the second antenna element 116 may have 5 dbi antennagain rating and provide 35 dbm effective isotropic radiated power(EIRP).

In some examples, the scope of the disclosure is not limited to thefirst RFID reader 102 having two antenna elements (i.e., the firstantenna element 114 and the second antenna element 116). In an exampleembodiment, the first RFID reader 102 may have only one antenna elementthat may be configured to transmit the first interrogation command andthe second interrogation command. In such an embodiment, the first RFIDreader 102 may be configured to separate the first interrogation commandand the second interrogation command by a predetermined time periodand/or polarization. For example, the first RFID reader 102 may beconfigured to separate the transmission of the first interrogationcommand and the second interrogation command by utilizing Time DivisionMultiple Access (TDMA) technology (which enables the separation of thetransmission by the predetermined time period). In another example, thefirst RFID reader 102 may be configured to separate the transmission ofthe first interrogation command and the second interrogation command byutilizing Orthogonal Frequency Division Multiple Access (OFDMA)technology. Similarly, the receptions of signals (e.g., the firstresponse signal and the second response signal) by such antenna may beseparated by the predetermined time period and/or polarization.

The structure and operation of the first RFID reader 102 is furtherdescribed in conjunction with FIG. 2.

In an example embodiment, the RFID reader 104 may include suitable logicand/or circuitry that may enable the RFID reader 104 to interrogate thesecond RFID tags 122 in the vicinity of the RFID reader 104, as isfurther described in FIG. 7. In some examples, the structure of the RFIDreader 104 may be similar to the first RFID reader 102. For example, theRFID reader 104 includes a first antenna element 120 that may beconfigured to generate the third signal and a second antenna element 118that may be configured to generate the second signal. Further, the RFIDreader 104 may be configured to utilize the second antenna element 118to transmit the second interrogation command to the second RFID tags 122in the vicinity of the RFID reader 104 over the second signal, as isfurther described in FIG. 7. Furthermore, the RFID reader 104 mayutilize the second antenna element 118 to receive the second responsesignal (that includes the second data) from the second RFID tags 122, asis further described in FIG. 7. In an embodiment, the second antennaelement 118 is configured to operate at a second transmit power that isbelow the first transmit power of the first antenna element 120 of thefirst RFID tag 110 of the RFID reader 104. In some examples, the secondantenna element 118 of the RFID reader 104 may have a similar structureto that of the second antenna element 116 of the first RFID reader 102.In some examples, the embodiments applicable on the second antennaelement 116 of the first RFID reader 102 may also be applicable on thesecond antenna element 118 of the RFID reader 104. In some examples, thesecond antenna element 118 of the RFID reader 104 may be configured todirect the second signal in a second predetermined direction. As such,the RFID reader 104 may scan the second RFID tags 122 positioned ortransiting through a location where the second signal is being directedby the second antenna element 118.

Additionally, or alternatively, the RFID reader 104 may include thefirst RFID tag 110. In an example embodiment, the first RFID tag 110 mayinclude a suitable logic and/or circuitry that may enable the first RFIDtag 110 to receive the first interrogation command from the first RFIDreader 102, as is further described in conjunction with FIG. 7. Inresponse to the first interrogation command, the first RFID tag 110 maybe configured to transmit the first data to the first RFID reader 102,as is further described in FIG. 7. In an example embodiment, the firstRFID tag 110 may include an integrated circuit (IC), a first antennaelement 120, and a substrate. In an example embodiment, the firstantenna element 120 and the IC are fabricated on the substrate. In anexample embodiment, the first antenna element 120 may have a similarstructure to that of the first antenna element 114 of the first RFIDreader 102. Further, the embodiments applicable on the first antennaelement 114 of the first RFID reader 102 are also applicable of thefirst antenna element 120 of the first RFID tag 110 of the RFID reader104. In some examples, the IC is communicatively coupled to the firstantenna element 120 through an interconnect on the substrate.Additionally, or alternately, the first RFID tag 110 may be associatedwith a unique identifier (ID) that may be stored in the IC. In someexamples, the unique ID of the first RFID tag 110 may correspond to anID that may be utilized to differentiate the first RFID tag 110 from theother first RFID tags of other RFID readers in the system environment100, and further to differentiate the other RFID readers from oneanother. For example, the unique ID for the first RFID tag 110 in theRFID reader 104 may be different from the unique ID of the first RFIDtag 126 in the second RFID reader 134. Some examples of the unique IDmay include a medium access control (MAC) Address, and/or the like. Insome examples, the first RFID tag 110 may be configured to operate invarious RF frequency bands such as, but not limited to, 3 MHz-30 MHz(the HF band (for example 13.56 MHz)) and/or 860 MHz-960 MHz (UHF band).In some example embodiments, the first RFID tag 110 may have a dedicatedpower source that may enable the first RFID tag 110 to communicate withone or more components of the system environment 100. In alternativeexample embodiments, the first RFID tag 110 may not have the dedicatedpower source. In such embodiments, the first RFID tag 110 may have apower coupler that is capable of inducing electrical charge when thefirst RFID tag 110 is brought in an RF field. The induced electricalcharge is thereafter used to power the first RFID tag 110 itself. Forexample, the first RFID tag 110 of the RFID reader 104 may induce powerwhen the first RFID tag 110 receives the first signal from the firstRFID reader 102. The structures of the first RFID tag 110 and the RFIDreader 104 are further described in conjunction with FIG. 3. In variousexamples, the RFID reader 104 may have various configurations. Forexample, the RFID reader 104 may have 30 dbm output power and provide 25dbm EIRP.

In an example embodiment, the RFID reader 104 may include suitable logicand/or circuitry that may enable the first RFID tag 110 of the RFIDreader 104 to interrogate the second RFID reader 134 via the firstantenna element 120 of the first RFID tag 110, as is further describedin FIG. 7. For example, the first antenna element 120 may be configuredto generate the third signal comprising the third interrogation signal.In an embodiment, the third interrogation command is transmitted, in asecond time interval, to the first RFID tag 126 of the second RFIDreader 134 through the first antenna element 120 operating at the firsttransmit power. In an embodiment, the second time interval occurssubsequent to the first time interval. Further, the RFID reader 104 mayutilize the first antenna element 120 to receive the third responsesignal (that includes the third data) from the second RFID reader 134,as is further described in FIG. 7. In some examples, the first antennaelement 120 of the RFID reader 104 may have a similar structure to thatof the first antenna element 114 of the first RFID reader 102. In someexamples, the embodiments applicable on the first antenna element 114 ofthe first RFID reader 102 may also be applicable on the first antennaelement 120 of the RFID reader 104. In some examples, the first antennaelement 120 of the RFID reader 104 may be configured to direct the thirdsignal in a third predetermined direction. As such, the RFID reader 104may scan the second RFID reader 134 positioned or transiting through alocation where the third signal is being directed by the first antennaelement 120.

In an example embodiment, the second RFID reader 134 may includesuitable logic and/or circuitry that may enable the second RFID reader134 to interrogate the second RFID tags 142 in the vicinity of thesecond RFID reader 134 and one or more third RFID readers in thevicinity of the second RFID reader 134. In some examples, the structureand operation of the second RFID reader 134 may be similar to the RFIDreader 104. For example, the second RFID reader 134 includes a firstantenna element 128 that may be configured to generate a third signalcomprising a third interrogation command directed towards a first RFIDtag of a third RFID reader (not shown) in the vicinity of the secondRFID reader 134, and a second antenna element 130 that may be configuredto generate the second signal comprising the second interrogationcommand directed towards second RFID tags 142 in the vicinity of thesecond RFID reader 134.

In an example embodiment, the RFID readers 104, 124 and the second RFIDreaders 134, 136, 138, 140 may be installed in one or more zones of thesystem environment 100. For example, the RFID readers 104, 124 may beinstalled in Level-1 of the system environment 100 and the second RFIDreaders 134, 136, 138, 140 may be installed in the Level-2 in the of thesystem environment 100. In an example embodiment, the RFID reader 104may be configured to interrogate the second RFID tags 122 in Level-1 inthe system environment 100 in a first time interval and to interrogatethe first RFID tag 126 of the second RFID reader 134 in Level-2 in thesystem environment 100 in a second time interval, where the second timeinterval occurs subsequent to the first time interval. Similarly, thesecond RFID reader 134 may be configured to interrogate the second RFIDtags 142 in Level-2 in the system environment 100. The second RFIDreader 134 may be configured to interrogate the second RFID tags 142 inLevel-2 in the system environment 100 in the first time interval and tointerrogate the first RFID tag of the third RFID reader in Level-3 (notshown) in the system environment 100 in the second time interval.

In an example embodiment, the central server 106 may include suitablelogic and/or circuitry that may enable the central server 106 to receivethe first data, the second data, and/or the third data from the firstRFID reader 102 via, for example but not limited to, the network 108. Insome examples, the central server 106 may utilize the first data, thesecond data, and/or the third data to track the one or more assets inthe system environment 100. Additionally, or alternatively, the centralserver 106 may utilize the first data, the second data, and/or the thirddata to monitor the availability of the one or more assets in the systemenvironment 100. In an example embodiment, the central server 106 maycorrespond to a computing device such as, but not limited to, a laptop,a server, or portable computing device.

The network 108 corresponds to a medium through which content andmessages may flow between various devices in the system environment 100(e.g., the first RFID reader 102 and central server 106). Examples ofthe network 108 may include wired and/or wireless networks, such as butnot limited to, a Wireless Fidelity (Wi-Fi) network, a Wireless AreaNetwork (WAN), a Local Area Network (LAN), and/or a Metropolitan AreaNetwork (MAN). Various devices in the system environment 100 can connectto the network 108 in accordance with various wired and wirelesscommunication protocols such as Transmission Control Protocol andInternet Protocol (TCP/IP), User Datagram Protocol (UDP), and 2G, 3G,4G, or 5G communication protocols.

FIG. 2 illustrates a block diagram of the first RFID reader 102,according to one or more embodiments described herein. In an exampleembodiment, the first RFID reader 102 may comprise a first processor202, a first memory unit 204, a first communication interface 206, afirst RFID reader unit 208, the first antenna element 114, the secondantenna element 116, a first noise cancellation unit 210, and a firstpower source unit 212.

The first processor 202 may be embodied as means including one or moremicroprocessors with accompanying digital signal processor(s), one ormore processor(s) without an accompanying digital signal processor, oneor more coprocessors, one or more multi-core processors, one or morecontrollers, processing circuitry, one or more computers, various otherprocessing elements including integrated circuits such as, but notlimited to, an application specific integrated circuit (ASIC) or fieldprogrammable gate array (FPGA), or some combination thereof.Accordingly, although illustrated in FIG. 2 as a single processor, in anembodiment, the first processor 202 may include a plurality ofprocessors and signal processing modules. The plurality of processorsmay be embodied on a single electronic device or may be distributedacross a plurality of electronic devices collectively configured tofunction as the circuitry of the first RFID reader 102. The plurality ofprocessors may be in operative communication with each other and may becollectively configured to perform one or more functionalities of thecircuitry of the first RFID reader 102 as described herein. In anexample embodiment, the first processor 202 may be configured to executeinstructions stored in the first memory unit 204 or otherwise accessibleto the first processor 202. These instructions, when executed by thefirst processor 202, may cause the circuitry of the first RFID reader102 to perform one or more of the functionalities, as described herein.

Whether configured by hardware, firmware/software methods, or by acombination thereof, the first processor 202 may include an entitycapable of performing operations according to embodiments of the presentdisclosure while configured accordingly. Thus, for example, when thefirst processor 202 is embodied as an ASIC, FPGA, or the like, the firstprocessor 202 may include specifically configured hardware forconducting one or more operations described herein. Additionally, oralternatively, when the first processor 202 is embodied as an executorof instructions, such as may be stored in the first memory unit 204, theinstructions may specifically configure the first processor 202 toperform one or more algorithms and operations described herein.

Thus, the first processor 202 used herein may refer to a programmablemicroprocessor, microcomputer or multiple processor chip or chips thatcan be configured by software instructions (applications) to perform avariety of functions, including the functions of the various embodimentsdescribed above. In some devices, multiple processors may be provideddedicated to wireless communication functions and one processordedicated to running other applications. Software applications may bestored in the internal memory before they are accessed and loaded intothe processors. The processors may include internal memory sufficient tostore the application software instructions. In many devices, theinternal memory may be a volatile or nonvolatile memory, such as flashmemory, or a mixture of both. The memory can also be located internal toanother computing resource (e.g., enabling computer readableinstructions to be downloaded over the Internet or another wired orwireless connection).

The first memory unit 204 may include suitable logic, circuitry, and/orinterfaces that are adapted to store a set of instructions that isexecutable by the first processor 202 to perform predeterminedoperations. Additionally, or alternately, the first memory unit 204 maybe configured to store the first data (obtained from the first RFID tag110 of the RFID reader 104) and the second data (obtained from thesecond RFID tags 112). Further, the first memory unit 204 may beconfigured to store a list of the RFID readers 104, 124 and/or thesecond RFID readers 134, 136, 138, 140 along with the respective uniqueID. Additionally or alternatively, the first memory unit 204 may beconfigured to store zone ID associated with the RFID readers 104, 124and the second RFID readers 134, 136, 138, 140. In an exampleembodiment, zone ID may be representative of zone in which the RFIDreader (e.g. 104, 124, etc.) and/or the second RFID reader (e.g., 134,136, 138, 140, etc.) is installed. In some examples, the unique ID maybe associated with the respective first RFID tag in the RFID readers104, 124 or the second RFID readers 134, 136, 138, 140. Example memoryimplementations may include, but are not limited to, a hard disk, randomaccess memory, cache memory, read only memory (ROM), erasableprogrammable read-only memory (EPROM) & electrically erasableprogrammable read-only memory (EEPROM), flash memory, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, a compact disc read only memory (CD-ROM), digitalversatile disc read only memory (DVD-ROM), an optical disc, circuitryconfigured to store information, or some combination thereof. In anexample embodiment, the first memory unit 204 may be integrated with thefirst processor 202 on a single chip, without departing from the scopeof the disclosure.

The first communication interface 206 may include suitable logic and/orcircuitry that may enable the first communication interface 206 tofacilitate transmission and reception of messages and data to and fromvarious devices. For example, the first communication interface 206 maybe communicatively coupled with the central server 106. Examples of thefirst communication interface 206 may include, but are not limited to,an antenna, an Ethernet port, a USB port, a serial port, or any otherport that can be adapted to receive and transmit data. The firstcommunication interface 206 may transmit and receive data and/ormessages in accordance with the various communication protocols, suchas, but not limited to, EPC global, DOD, I2C, TCP/IP, UDP, and 2G, 3G,4G or 5G communication protocols.

In some examples, the first communication interface 206 may facilitatethe communication with the first RFID tag 110 of the RFID reader 104 andthe second RFID tags 112 in the vicinity of the first RFID reader 102.In some examples, the first communication interface 206 may becommunicatively coupled with the first antenna element 114 and thesecond antenna element 116. The first antenna element 114 may bepositioned to be spatially apart from the second antenna element 116.Such positioning of the first antenna element 114 and the second antennaelement 116 (spatially apart from each other) may reduce theinterference between the signals transmitted/received via the firstantenna element 114 and the second antenna element 116. For example, thefirst antenna element 114 and the second antenna element 116 spatiallyprovide 40 dB isolation. In some examples, the first communicationinterface 206 may be configured to transmit/receive data through thefirst antenna element 114 and the second antenna element 116 byutilizing one or more of EPC global communication standards or DODcommunication standards.

The first RFID reader unit 208 may include suitable logic and/orcircuitry for reading the first data and the second data from the firstRFID tag 110 of the RFID reader 104 and the second RFID tags 112 in thevicinity of the first RFID reader 102, respectively. To read the firstdata and the second data from the first RFID tag 110 of the RFID reader104 and the second RFID tags 112, the first RFID reader unit 208 maycause the first antenna element 114 and the second antenna element 116to transmit the first interrogation command and the second interrogationcommand, respectively. Further, prior to transmitting the firstinterrogation command the second interrogation command, the first RFIDreader unit 208 may cause the first communication interface 206 tomodulate the first interrogation command and the second interrogationcommand, over the first signal and the second signal, using the one ormore modulation techniques (such as ASK and PJM). In response to thefirst interrogation command and the second interrogation command, thefirst RFID reader unit 208 may receive the first data and the seconddata from the first RFID tag 110 of the RFID reader 104 and the secondRFID tags 112 in the vicinity of the first RFID reader 102.

In some examples, the first RFID reader unit 208 may include one or moreof filters, analog to digital (A/D) converters, Digital to Analog (D/A)convertors, matching circuits, amplifiers, and/or tuners that may enablethe first RFID reader unit 208 to transmit data (e.g., the firstinterrogation command and the second interrogation command) and receivedata (e.g., the first data and the second data) over the one or morefrequency bands through the first antenna element 114 and the secondantenna element 116. The first RFID reader unit 208 may be implementedusing one or more of Application Specific Integrated Circuit (ASIC) andField Programmable Gate Array (FPGA).

The first noise cancellation unit 210 may include suitable logic and/orcircuitry that may reduce the interference amongst the signals (e.g.,the first signal, the second signal, the first response signal, and thesecond response signal) transmitted/received by the first antennaelement 114 and the second antenna element 116. In some examples, thefirst noise cancellation unit 210 may include one or more filters, oneor more phase shifters and/or the like. The structure and operation ofthe first noise cancellation unit 210 is further described inconjunction with FIG. 4. The operation of the first RFID reader 102 isfurther described in conjunction with FIG. 9.

In an embodiment, the first power source unit 212 may include suitablelogic and/or circuitry that may provide power to the first RFID reader102.

FIG. 3 illustrates a block diagram of an example RFID reader 104,according to one or more embodiments described herein. The RFID reader104 may include the first RFID tag 110, the second processor 302, afirst common memory unit 304, a second communication interface 310, asecond noise cancellation unit 312, a second RFID reader unit 314, afirst RFID encoder unit 316, and a second power source unit 324. In someexamples, the second communication interface 310 may further be coupledto the first antenna element 120. In an example embodiment, the firstRFID tag 110 may further include a third processor 318, a thirdcommunication interface 320, and an Input/Output (I/O) interface unit322. The third communication interface 320 may be further coupled to thesecond antenna element 118.

The second processor 302 may be embodied as means including one or moremicroprocessors with accompanying digital signal processor(s), one ormore processor(s) without an accompanying digital signal processor, oneor more coprocessors, one or more multi-core processors, one or morecontrollers, processing circuitry, one or more computers, various otherprocessing elements including integrated circuits such as, for example,an application specific integrated circuit (ASIC) or field programmablegate array (FPGA), or some combination thereof. Accordingly, althoughillustrated in FIG. 3 as a single processor, in an embodiment, thesecond processor 302 may include a plurality of processors and signalprocessing modules. The plurality of processors may be embodied on asingle electronic device or may be distributed across a plurality ofelectronic devices collectively configured to function as the circuitryof the RFID reader 104. The plurality of processors may be in operativecommunication with each other and may be collectively configured toperform one or more functionalities of the circuitry of the RFID reader104, as described herein. In an example embodiment, the second processor302 may be configured to execute instructions stored in the first commonmemory unit 304 or otherwise accessible to the second processor 302.These instructions, when executed by the second processor 302, may causethe circuitry of the RFID reader 104 to perform one or more of thefunctionalities, as described herein.

Whether configured by hardware, firmware/software methods, or by acombination thereof, the second processor 302 may include an entitycapable of performing operations according to embodiments of the presentdisclosure while configured accordingly. Thus, for example, when thesecond processor 302 is embodied as an ASIC, FPGA, or the like, thesecond processor 302 may include specifically configured hardware forconducting one or more operations described herein. Alternatively, asanother example, when the second processor 302 is embodied as anexecutor of instructions, such as may be stored in the first commonmemory unit 304, the instructions may specifically configure the secondprocessor 302 to perform one or more algorithms and operations describedherein.

Thus, the second processor 302 used herein may refer to a programmablemicroprocessor, microcomputer or multiple processor chip or chips thatcan be configured by software instructions (applications) to perform avariety of functions, including the functions of the various embodimentsdescribed above. In some devices, multiple processors may be provideddedicated to wireless communication functions and one processordedicated to running other applications. Software applications may bestored in the internal memory before they are accessed and loaded intothe processors. The processors may include internal memory sufficient tostore the application software instructions. In many devices, theinternal memory may be a volatile or nonvolatile memory, such as flashmemory, or a mixture of both. The memory can also be located internal toanother computing resource (e.g., enabling computer readableinstructions to be downloaded over the Internet or another wired orwireless connection).

The first common memory unit 304 may include suitable logic, circuitry,and/or interfaces that are adapted to store a set of instructions thatis executable by the second processor 302 to perform predeterminedoperations. Additionally, or alternately, the first common memory unit304 may be configured to store the second data (received from the secondRFID tags 122). In some examples, a collection of the second data isreferred to as the first data. Additionally, or alternately, the firstcommon memory unit 304 may be configured to store the unique IDassociated with the first RFID tag 110. Example memory implementationsinclude, but are not limited to, a hard disk, random access memory,cache memory, read only memory (ROM), erasable programmable read-onlymemory (EPROM) & electrically erasable programmable read-only memory(EEPROM), flash memory, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, a compact disc read onlymemory (CD-ROM), digital versatile disc read only memory (DVD-ROM), anoptical disc, circuitry configured to store information, or somecombination thereof. In an example embodiment, the first common memoryunit 304 may be integrated with the second processor 302 on a singlechip, without departing from the scope of the disclosure.

Additionally, or alternately, the first common memory unit 304 may havea first partition 306 and a second partition 308. The first partition306 may include the one or more computer executable instructions thatthe second processor 302 may execute to perform the predeterminedoperation (e.g., operating the RFID reader 104). The second partition308 may correspond to a partition that stores the first data inaccordance with the EPC global standards. In an example embodiment, asdiscussed, the first data is collection of the second data, accordingly,the second partition 308 may store the second data. In an exampleembodiment, the second partition 308 may be accessible to both thesecond processor 302 and the first RFID tag 110. In some examples, thescope of the disclosure is not limited to the second partition 308storing the first data per the EPC global standards. In an exampleembodiment, the first data may be stored in accordance with otherpartition table standards.

The second communication interface 310 may correspond to a communicationinterface that may facilitate transmission and reception of messages anddata to and from various devices. For example, through the secondcommunication interface 310, the RFID reader 104 may be configured tocommunicate with the second RFID tags 122. Examples of the secondcommunication interface 310 may include, but are not limited to, anantenna, an Ethernet port, a USB port, a serial port, or any other portthat can be adapted to receive and transmit data. The secondcommunication interface 310 may transmit and receive data and/ormessages in accordance with the various communication protocols, such asbut not limited to, EPC global, and DOD communication protocols.

Additionally, or alternatively, the second communication interface 310is communicatively coupled with the first antenna element 120. In someexamples, the second communication interface 310 may be configured totransmit/receive data through the first antenna element 120 by utilizingone or more EPC global or DOD communication standards.

The second noise cancellation unit 312 may be similar to the first noisecancellation unit 210. For example, the second noise cancellation unit312 may include suitable logic and/or circuitry that may reduce theinterference amongst the signals (e.g., the first signal, the secondsignal, the first response signal, the second response signal)received/transmitted through the first antenna element 120 and thesecond antenna element 118. Further, structural details of the secondnoise cancellation unit 312 described in conjunction with FIG. 4 arealso applicable on the first noise cancellation unit 210. Additionally,or alternatively, the embodiments applicable on the second noisecancellation unit 312 are also applicable on the first noisecancellation unit 210.

The second RFID reader unit 314 may be similar to the first RFID readerunit 208 structurally and functionally. For example, the second RFIDreader unit 314 may include suitable logic and circuitry for reading thesecond data from the second RFID tags 122, as is further described inFIG. 7. To read the second data from the second RFID tags 122, thesecond RFID reader unit 314 may cause the first antenna element 120 totransmit the second interrogation command to the second RFID tags 122,as is further described in FIG. 7. Further, the second RFID reader unit314 may also cause the second communication interface 310 to modulatethe second interrogation command using the one or more modulationtechniques (such as ASK and PJM) prior to transmitting the secondinterrogation command on the one or more frequency bands. In response tothe second interrogation command, the second RFID reader unit 314 mayreceive the second data from the second RFID tags 122, as is furtherdescribed in FIG. 7.

The first RFID encoder unit 316 may include suitable logic, and/orcircuitry for encoding data in the second partition 308 of the firstcommon memory unit 304. In some example embodiments, the first RFIDencoder unit 316 encodes the data in the second partition 308 of thefirst common memory unit 304, according to one or more of ElectronicProduct Code (EPC) or Department of Defense (DOD) formats. For example,the first RFID encoder unit 316 may be configured to encode the seconddata (received from the second RFID tags 122) in the second partition308 of the first common memory unit 304. In some examples, the scope ofthe disclosure is not limited to the first RFID encoder unit 316encoding the second data in the first common memory unit 304. In anexample embodiment, the first RFID encoder unit 316 may only store thesecond data in the first common memory unit 304 per one or morepartition standards such as NTFS and/or FAT that are not encoded.

The third processor 318 may be embodied as means including one or moremicroprocessors with accompanying digital signal processor(s), one ormore processor(s) without an accompanying digital signal processor, oneor more coprocessors, one or more multi-core processors, one or morecontrollers, processing circuitry, one or more computers, various otherprocessing elements including integrated circuits such as, for example,an application specific integrated circuit (ASIC) or field programmablegate array (FPGA), or some combination thereof. Accordingly, althoughillustrated in FIG. 3 as a single processor, in an embodiment, the thirdprocessor 318 may include a plurality of processors and signalprocessing modules. The plurality of processors may be embodied on asingle electronic device or may be distributed across a plurality ofelectronic devices collectively configured to function as the circuitryof the first RFID tag 110. The plurality of processors may be inoperative communication with each other and may be collectivelyconfigured to perform one or more functionalities of the circuitry ofthe first RFID tag 110, as described herein.

Whether configured by hardware, firmware/software methods, or by acombination thereof, the third processor 318 may include an entitycapable of performing operations according to embodiments of the presentdisclosure while configured accordingly. Thus, for example, when thethird processor 318 is embodied as an ASIC, FPGA, or the like, the thirdprocessor 318 may include specifically configured hardware forconducting one or more operations described herein. Alternatively, asanother example, when the third processor 318 is embodied as an executorof instructions, such as may be stored in the first common memory unit304, the instructions may specifically configure the third processor 318to perform one or more algorithms and operations described herein.

Thus, the third processor 318 used herein may refer to a programmablemicroprocessor, microcomputer or multiple processor chip or chips thatcan be configured by software instructions (applications) to perform avariety of functions, including the functions of the various embodimentsdescribed above. In some devices, multiple processors may be provideddedicated to wireless communication functions and one processordedicated to running other applications. Software applications may bestored in the internal memory before they are accessed and loaded intothe processors. The processors may include internal memory sufficient tostore the application software instructions. In many devices, theinternal memory may be a volatile or nonvolatile memory, such as flashmemory, or a mixture of both. The memory can also be located internal toanother computing resource (e.g., enabling computer readableinstructions to be downloaded over the Internet or another wired orwireless connection).

The third communication interface 320 may facilitate transmission andreception of messages and data to and from various devices. For example,through the third communication interface 320, the first RFID tag 110may be configured to communicate with the first RFID reader 102 and/orthe second RFID reader 134. The third communication interface 320transmits and receives data and/or messages in accordance with thevarious communication protocols, such as, EPC global, and DODcommunication protocols.

Additionally, or alternatively, the third communication interface 320 iscommunicatively coupled with the second antenna element 118. In someexamples, the third communication interface 320 may be configured totransmit/receive data through the second antenna element 118 byutilizing one or more EPC global or DOD communication protocols.

The I/O interface unit 322 may include suitable logic and/or circuitrythat may be configured to enable communication between the first RFIDtag 110 and the first common memory unit 304, in accordance with one ormore device communication protocols such as, but not limited to, I2Ccommunication protocol, Serial Peripheral Interface (SPI) communicationprotocol, Serial communication protocol, Control Area Network (CAN)communication protocol, and 1-Wire® communication protocol. In someexamples, the I/O interface unit 322 may be configured to retrieve thefirst data or the portion of the first data from the first common memoryunit 304 by utilizing the one or more device communication protocol.Further, the I/O interface unit 322 may be configured to transform theretrieved first data, in accordance with the EPC global, DOD standards.Some examples of the I/O interface unit 322 may include, but not limitedto, a Data Acquisition (DAQ) card, an electrical drives driver circuit,and/or the like.

In an embodiment, the second power source unit 324 may include suitablelogic and/or circuitry that may provide power to the RFID reader 104and/or the first RFID tag 110.

The structure of the second RFID reader 134 and/or other RFID readers124, 136, 138, 140 in the mesh topology of the system environment 100may be similar to the structure of the RFID reader 104 described herein.For example, the structure of the second RFID reader 134 may be similarto structure of the RFID reader 104.

FIG. 4 illustrates a block diagram of the second noise cancellation unit312, according to one or more embodiments described herein.

The second noise cancellation unit 312 includes a coupler 402, anamplitude attenuator 404, a phase shifter 406, and a combiner 408. In anexample embodiment, the coupler 402 may be communicatively coupled to aninput channel 410 and the second antenna element 118. The coupler 402may be communicatively coupled to the amplitude attenuator 404. Theamplitude attenuator 404 may be further coupled to the phase shifter406, and the phase shifter 406 may be further coupled to the combiner408. The combiner 408 may be communicatively coupled to the firstantenna element 120 and the second communication interface 310.

The coupler 402 may include suitable logic and/or circuitry that mayenable the coupler 402 to retrieve a portion of the second signal (thatmay include the second interrogation command) to be transmitted via thesecond antenna element 118. In an example embodiment, the coupler 402may correspond to a three terminal microwave device that may include afirst terminal 412, a second terminal 414, and a third terminal 416. Insome examples, the first terminal 412 may be coupled to the inputchannel 410, the second terminal 414 may be coupled to the secondantenna element 118, and the third terminal 416 may be coupled to theamplitude attenuator 404. In an example embodiment, the input channel410 may correspond to a signal path that may couple the secondcommunication interface 310 with the coupler 402. The input channel 410may correspond to a conduit/waveguide through which the secondcommunication interface 310 may transmit the third signal to the coupler402. In an example embodiment, the coupler 402 may be configured totransmit the portion of the second signal to the amplitude attenuator404 through the third terminal 416. Some examples of the coupler 402 mayinclude, but not limited to, a forward-wave coupler, a backward-wavecoupler, a hybrid coupler, and/or the like.

The amplitude attenuator 404 may include suitable logic and/or circuitryto attenuate the amplitude of the portion of the second signal receivedfrom the coupler 402 to generate an attenuated portion of the secondsignal. In some examples, the amplitude attenuator 404 may include oneor more resistors arranged in one or more configurations, such as pi-padconfiguration and T-pad configuration. The one or more resistors mayfacilitate the attenuation of the portion of the second signal. Someexamples of the amplitude attenuator 404 may include, but are notlimited to, an active attenuator, a passive attenuator, π-typeunbalanced attenuator circuit, π-type balanced attenuator circuit,T-type unbalanced attenuator circuit, and/or T-type balanced attenuatorcircuit.

The phase shifter 406 may include suitable logic and/or circuitry toshift phase of the attenuated portion of the second signal by apredetermined amount to generate a phase shifted portion of the secondsignal. For example, the phase shifter 406 may shift the phase of theattenuated portion of the second signal by, for example but not limitedto, 180 degrees. In some examples, the phase shifter 406 may beconfigured to add a propagation delay to the attenuated portion of thesecond signal in order to shift the phase of the attenuated the portionof the second signal. Some examples of the phase shifter 406 mayinclude, but not limited to, micro-electromechanical system (MEMS) phaseshifter, an analog phase shifter, a digital phase shifter, an activephase shifter, a passive phase shifter, and/or the like.

The combiner 408 may include suitable logic and/or circuitry that mayenable the combiner 408 to combine one or more signals. In an exampleembodiment, the combiner 408 may be a three terminal microwave devicethat may include a fourth terminal 418, a fifth terminal 420, and asixth terminal 422. The fourth terminal 418 may be communicativelycoupled to the phase shifter 406 and may be configured to receive thephase shifted portion of the second signal. Further, the fifth terminal420 may be coupled to the first antenna element 120, and the sixthterminal 422 may be coupled to the second communication interface 310.The combiner 408 may be configured to combine the phase shifted portionof the second signal and the third response signal received from thefirst antenna element 120 to generate a noise free third responsesignal.

In operation, the coupler 402 may be configured to retrieve the portionof the second signal from the second signal (that includes the secondinterrogation command) to be transmitted via the second antenna element118. The coupler 402 may be configured to transmit the portion of thesecond signal to the amplitude attenuator 404. The amplitude attenuator404 may be configured to attenuate the amplitude of the portion of thesecond signal to generate the attenuated portion of the second signal.In an example embodiment, the amplitude attenuator 404 may be configuredto transmit the attenuated portion of the second signal to the phaseshifter 406.

In some examples, the phase shifter 406 may be configured to shift thephase of the attenuated portion of the second signal by thepredetermined amount. For example, the phase shifter 406 may beconfigured to phase shift the attenuated portion of the second signal by180 degrees to generate phase shifted portion of the second signal.Thereafter, phase shifter 406 may be configured to transmit the phaseshifted portion of the second signal to the combiner 408. In an exampleembodiment, the combiner 408 may be configured to combine the phaseshifted portion of the second signal with the third response signal(received from the first RFID tag 126 of the second RFID reader 134).

In some examples, the third response signal received by the firstantenna element 120 may comprise noise because of the interferencecaused by the transmission of the second signal from the second antennaelement 118. For example, the third response signal may include theportion of the second signal (as noise). As discussed above, the phaseshifted portion of the second signal may be 180 degrees out of phase,and the third response signal (received via the first antenna element120) includes the portion of the second signal. Therefore, when thecombiner 408 adds the third response signal with the phase shiftedportion of the second signal, the phase shifted portion of the secondsignal may cancel out with the portion of the second signal present inthe third response signal. Accordingly, the combiner 408 may generatethe noise free third response signal.

In some examples, the scope of the disclosure is not limited to havingone second noise cancellation unit 312 in the RFID reader 104. In anexample embodiment, the RFID reader 104 may include multiple noisecancellation units. For instance, the RFID reader 104 may includeanother noise cancellation unit for the second antenna element 118. Theother noise cancellation unit may be configured to generate a noise freesecond response signal (received from the second RFID tags 122) based onthe portion of the third signal (containing the third interrogationcommand) retrieved from the third signal transmitted via the firstantenna element 120.

FIG. 5 illustrates an example timing diagram 500 of operation ofdifferent RFID readers in a dense reader mode (DRM), according to one ormore embodiments described herein. The timing diagram illustrated inFIG. 5 depicts the operation of 3 RFID readers, for example, the firstRFID reader 102, the RFID reader 104, and the second RFID reader 134, inthe DRM mode. The DRM mode allows for the operation of the first RFIDreader 102, the RFID reader 104, and/or the second RFID reader 134located in close proximity of each other without causing interrogatorinterference by the interrogation commands transmitted by the respectiveRFID readers. In the DRM mode, the first RFID reader 102, the RFIDreader 104, and/or the second RFID reader 134 are allocated differentfrequency channels to communicate with the respective first RFID tagsand/or the respective one or more second RFID tags, such that no twoREID readers are transmitting the respective interrogation commands onthe same frequency channel, thereby reducing interference caused withindifferent zones of the mesh topology of the system environment 100.

In an embodiment, the RFID readers implement frequency hopping in theDRM mode. For example, as illustrated in FIG. 5, the first RFID reader102 hops from the first frequency channel F1 in the first time intervalT1 to the fourth frequency channel F4 in the second time interval T2.Similarly, the RFID reader 104 hops from the third frequency channel F3in the first time interval T1 to the sixth frequency channel F6 in thesecond time interval T2. Further, the second RFID reader 134 hops fromthe fifth frequency channel F5 in the first time interval T1 to thesecond frequency channel F2 in the second time interval T2. Therefore,at a given time interval, all RFID readers are transmitting respectiveinterrogation commands in different frequency channels, thereby reducinginterrogator interference that may be caused by two or more RFID readersfunctioning in close proximity with each other in the mesh topology ofthe system environment 100 disclosed herein.

FIG. 6 illustrates an example timing diagram 600 of transmission of thefirst interrogation command, the second interrogation command, the thirdinterrogation command, and a fourth interrogation command, according toone or more embodiments described herein.

The example timing diagram 600 includes a master clock cycle 602, afirst timing signal 604 depicting transmission of the firstinterrogation command, a second timing signal 606 depicting reception ofthe first response signal, a third timing signal 608 depictingtransmission of the second interrogation command, a fourth timing signal610 depicting reception of the second response signal, a fifth timingsignal 612 depicting transmission of the third interrogation command, asixth timing signal 614 depicting reception of the third responsesignal, a seventh timing signal 616 depicting transmission of the fourthinterrogation command, and an eighth timing signal 618 depictingreception of a fourth response signal.

It can be observed from the example timing diagram 600 that the firstRFID reader 102 may cause the transmission of the first interrogationcommand in the first time interval T1 (as depicted by the first timingsignal 604). Additionally, or alternatively, in the first time intervalT1, the first RFID reader 102 may receive the first response signal (asdepicted by the second timing signal 606).

Further, it can be observed from the example timing diagram 600 that theRFID reader 104 may cause the transmission of the third interrogationcommand in the second time interval T2 (as depicted by the third timingsignal 608). Additionally, or alternatively, in the second time intervalT2, the RFID reader 104 may receive the third response signal (asdepicted by the fourth timing signal 610).

Furthermore, it can be observed from the example timing diagram 600 thatthe RFID reader 104 may cause the transmission of the secondinterrogation command in the first time interval T1 (as depicted by thefifth timing signal 612). In an embodiment, the completion oftransmission of the second interrogation command in the first timeinterval T1 and the start of the transmission of the third interrogationcommand in the second time interval T2 are separated by a predeterminedtime period, for example, of about 200 milliseconds. Accordingly, theRFID reader 104 may cause alternating transmission of the secondinterrogation command and the third interrogation command. Additionally,or alternatively, in the first time interval T1, the RFID reader 104 mayreceive the second response signal (as depicted by the sixth timingsignal 614).

Furthermore, it can be observed from the example timing diagram 600 thata fourth RFID reader may cause the transmission of the fourthinterrogation command in the second time interval T2 (as depicted by theseventh timing signal 616). In an embodiment, the completion oftransmission of the second interrogation command in the first timeinterval T1 and the start of the transmission of the fourthinterrogation command in the second time interval T2 are separated bythe predetermined time period, for example, of about 200 milliseconds.Additionally, or alternatively, in the second time interval T2, thefourth RFID reader may receive the fourth response signal (as depictedby the eighth timing signal 618).

Because the reception of the first response signal may overlap with thetransmission of the first interrogation command (transmitted over thefirst signal), the first response signal may interfere with the firstsignal. Accordingly, the first noise cancellation unit 210 may removethe noise from the first response signal. Similarly, because thereception of the second response signal may overlap with thetransmission of the second interrogation command (transmitted over thesecond signal), the second response signal may interfere with the secondsignal. Accordingly, the second noise cancellation unit 312 may removethe noise from the second response signal.

FIG. 7 illustrates a flowchart 700 to operate the RFID reader 104,according to one or more embodiments described herein. At step 702, theRFID reader 104 may include means such as the third processor 318 of thefirst RFID tag 110, the third communication interface 320, the firstantenna element 120, and/or the like for receiving, in a first timeinterval, a first interrogation command from the first RFID reader 102.In an embodiment, the first antenna element 120 is configured to operateat a first transmit power. At step 704, the RFID reader 104 may includemeans such as the third processor 318, the third communication interface320, the first antenna element 120, and/or the like for transmitting, inthe first time interval, the first response signal to the first RFIDreader 102, in response to receiving the first interrogation command.Because the first interrogation command includes the unique ID of thefirst RFID tag 110 of the RFID reader 104, the first RFID reader 102 mayreceive the first response signal from the first RFID tag 110 of theRFID reader 104 that is associated with the unique ID. For example, thefirst RFID reader 102 may receive the first response signal from thefirst RFID tag 110 in the RFID reader 104. In some examples, the firstresponse signal may include the first data.

At step 706, the RFID reader 104 may include means, such as the secondprocessor 302, the second communication interface 310, the second RFIDreader unit 314, the second antenna element 118, and/or the like fortransmitting, in the first time interval, the second interrogationcommand to the one or more second RFID tags 122 in the vicinity of theRFID reader 104. In an embodiment, the second antenna element 118 isconfigured to operate at a second transmit power. In an embodiment, thesecond transmit power of the second antenna element 118 is below thefirst transmit power of the first antenna element 120. In an embodiment,the second signal including the second interrogation command istransmitted in the second predetermined direction. Accordingly, as andwhen the second RFID tags 122 pass through the location where the RFIDreader 104 directs the second signal, the second RFID tags 122 mayreceive the second interrogation command.

At step 708, the RFID reader 104 may include means, such as the secondprocessor 302, the second communication interface 310, the second RFIDreader unit 314, the second antenna element 118, and/or the like forreceiving the second response signal from the one or more second RFIDtags 122 in the first time interval, in response to transmitting thesecond interrogation command. As discussed above, in some examples, thesecond RFID tags 122 may correspond to passive RFID tags. Accordingly,when the second RFID tags 122 receive the second signal, the secondsignal may cause the second RFID tags 122 to induce charge. The inducedcharge may be used by the second RFID tags 122 to power itself (alsoreferred to as power harvesting). Thereafter, the second RFID tags 122may utilize the induced charge to transmit the second response signal.In some examples, where the second RFID tags 122 may correspond toactive RFID tags, the second RFID reader unit 314 may directly transmitthe second interrogation command over the second signal. Upon receivingthe second interrogation command, the second RFID tags 122 may utilizethe power stored in the battery (in the second RFID tag 122) to transmitthe second response signal.

In some examples, the second RFID reader unit 314 may be configured toutilize standards such as, but not limited to, EPC global standards totransmit the second interrogation command. For example, the secondinterrogation command may include “Read” command. Such interrogationcommand (comprising the “Read” command), when received by an RFID tag,may cause the RFID tag to retrieve and transmit data stored in the RFIDtag. For example, upon receiving such interrogation command (comprisingthe “Read” command), the second RFID tags 122 may retrieve and transmitthe second data stored in the second RFID tags 122.

In some examples, the second RFID reader unit 314 may be configured tocause the second antenna element 118 to transmit the secondinterrogation command (over the second signal) continuously. In anotherembodiment, the second RFID reader unit 314 may be configured to causethe second antenna element 118 to the transmit the second interrogationcommand (over the second signal) periodically after a predetermined timeperiod. For example, the second RFID reader unit 314 may be configuredto cause the second antenna element 118 to transmit the secondinterrogation command after every 200 milliseconds (ms). In an exampleembodiment, the second RFID reader unit 314 may be configured to receivethe second response signal from the second RFID tags 122, in accordancewith the EPC global and/or DOD standards. In some examples, the secondresponse signal may include the second data. In some examples, thesecond data may correspond to the data stored in the second RFID tags122. Further, the second RFID reader unit 314 may be configured to storethe second data in the first common memory unit 304.

At step 710, the RFID reader 104 may include means such as the thirdprocessor 318, the third communication interface 320, the first antennaelement 120, and/or the like for transmitting, in the second timeinterval, a third interrogation command to the first RFID tag 126 of thesecond RFID reader 134 through the first antenna element 120 operatingat the first transmit power. In an embodiment, the second time intervaloccurs subsequent to the first time interval and may be separated by apredetermined time duration of about 200 ms. In an example embodiment,the second RFID reader unit 314 may cause the first antenna element 120to transmit the third interrogation command over the third signal. In anexample embodiment, the second RFID reader unit 314 may utilize EPCglobal and the DOD standards to transmit the third interrogation commandover the third signal.

In an example embodiment, prior to transmitting the third interrogationcommand, the second RFID reader unit 314 may be configured to select asecond RFID reader (e.g., second RFID reader 134) of the second RFIDreaders 134, 136, 138, 140, etc. In some examples, the second RFIDreader unit 314 may sequentially select the second RFID reader 134 fromthe list of the second RFID readers 134, 136, 138, 140 stored in thefirst common memory unit 304. The following table illustrates an examplelist of the second RFID readers 134, 136, 138, 140 stored on the firstcommon memory unit 304:

TABLE 1 List of the second RFID readers List of Second RFID readersUnique ID Zone ID Location Second RFID reader 1234567890 L1 x: 5, y: 6,z: 10 134 Second RFID reader 0987654321 L2 X: 7, y: 10, z: 25 136

Referring to Table 1, it can be observed that the list of the secondRFID readers 134, 136 may include the unique ID associated withrespective first RFID tag associated with the second RFID readers 134,136. Further, Table 1 depicts a location at which the second RFIDreaders 134, 136 are positioned with respect to the RFID reader 104. Forexample, the second RFID reader 134 is located at coordinates (5, 6,10), while the second RFID reader 136 is located at coordinates (7, 10,25), with respect to the RFID reader 104. In some examples, the Table 1further illustrates level ID, where the second RFID readers 134, 136 areinstalled.

In some examples, the second RFID reader unit 314 may sequentiallyselect the second RFID reader 134 from the list of the second RFIDreaders (e.g., table 1). Additionally, the second RFID reader unit 314may be configured to retrieve the unique ID associated with first RFIDtag in the selected second RFID reader 134 and the location of theselected second RFID reader 134. Thereafter, the second RFID reader unit314 may be configured to include the unique ID in the thirdinterrogation command. Further, the second RFID reader unit 314 maycause the first antenna element 120 to direct the third signal in adirection of the retrieved location. Subsequently, the second RFIDreader unit 314 transmits the third interrogation command.

In some examples, the scope of the disclosure is not limited to thetransmitting the third interrogation signal only based on thecoordinates of the second RFID readers 134, 136. In an exampleembodiment, the RFID reader 104 may transmit the third interrogationsignal based on a level in the mesh topology in which the second RFIDreaders 134, 136 are installed. In an embodiment, the levels in the meshtopology correspond to different zones covered by different RFID readersof the system environment 100. For example, based on the zone in whichthe second RFID reader 134 (e.g.,) is installed, the second RFID readerunit 314 may be configured to retrieve the coordinates at which thesecond RFID reader 134 is installed. Subsequently, the second RFIDreader unit 314 transmits the third interrogation command.

In some examples, the scope of the disclosure is not limited to thethird interrogation command only including the unique ID of the firstRFID tag 126 included in the second RFID reader 134. In an exampleembodiment, the second RFID reader unit 314 may further include anaddress of a memory unit in the second RFID reader 134 where the secondRFID reader 134 intends to read the third data. The following tableillustrates an example third interrogation command:

TABLE 2 An example third interrogation command Command Unique ID AddressRead 1234567890 34AD

Accordingly, in an example embodiment, the third interrogation commandmay be different from the second interrogation command (transmitted atthe step 706). For example, in addition to the “Read” command, the thirdinterrogation command may include the unique ID associated with thefirst RFID tag 126 (included in the selected second RFID reader 134)that is to be interrogated, and/or the address of the memory unit fromwhere the RFID reader 104 intends to read the third data.

In an embodiment, the third processor 318 may cause the first antennaelement 120 to transmit the third interrogation command in the secondtime interval, subsequent to the second processor 302 causing the secondantenna element 118 to transmit the second interrogation command in thefirst time interval. More particularly, the third processor 318 maycause the first antenna element 120 to transmit the third interrogationcommand during the predetermined time period (i.e., 200 ms).Accordingly, the RFID reader 104 may cause alternating transmission ofthe second interrogation command and the third interrogation command.FIG. 6 illustrates a timing diagram 600 depicting an exampletransmission of the second interrogation command and the thirdinterrogation command.

In an embodiment, the second RFID reader unit 314 determines whether thethird interrogation signal has been transmitted to each of the secondRFID readers 134, 136 in level 2 of the mesh topology of the systemenvironment 100. If the second RFID reader unit 314 determines that thethird interrogation command has been transmitted to each of the secondRFID readers 134, 136, the second RFID reader unit 314 may be configuredto end the execution of the flowchart 700. However, if the second RFIDreader unit 314 determines that the third interrogation command has notbeen transmitted to each of the second RFID readers 134, 136, the secondRFID reader unit 314 may be configured to repeat the step 710.

At step 712, the RFID reader 104 may include means such as the thirdprocessor 318, the third communication interface 320, the first antennaelement 120, and/or the like for receiving, in the second time interval,the third response signal from the second RFID reader 134. In anembodiment, the third response signal comprises third data.

In an embodiment, the first RFID reader 102 receives the first data, thesecond data, and the third data from the RFID reader 104. In anembodiment, the first RFID reader 102 transmits the first data, thesecond data, and the third data to the central server 106 via thenetwork 108. In some examples, the second processor 302 may transmit thefirst data, the second data, and the third data after the second RFIDreader unit 314 has interrogated the first RFID tag in each of thesecond RFID readers 134, 136. In another embodiment, the secondprocessor 302 may transmit the first data, the second data, and thethird data as and when the second RFID reader unit 314 receives thethird data from the first RFID tag 126 in the second RFID reader 134.

FIG. 8 illustrates a flowchart 800 to operate the RFID reader 104 in thedense reader mode (DRM), according to one or more embodiments describedherein.

At step 802, the RFID reader 104 may include means such as the thirdprocessor 318 of the first RFID tag 110, the third communicationinterface 320, the second RFID reader unit 314, the first antennaelement 120, the second antenna element 118, and/or the like forconfiguring the RFID reader 104 in the DRM mode. In an embodiment, asdescribed in conjunction with FIG. 5, the RFID reader 104 operates inthe DRM mode to avoid causing interference in the communication of otherRFID readers operating in the vicinity of the RFID reader 104.

At step 804, the RFID reader 104 may include means such as the thirdprocessor 318 of the first RFID tag 110, the third communicationinterface 320, the second RFID reader unit 314, the first antennaelement 120, the second antenna element 118, and/or the like forscanning for RFID tags, for example, the first RFID tag 126 of thesecond RFID reader 134 and/or the one or more second RFID tags 122 inthe vicinity of the RFID reader 104.

At step 806, the RFID reader 104 may include means such as the thirdprocessor 318 of the first RFID tag 110, the third communicationinterface 320, the second RFID reader unit 314, the first antennaelement 120, the second antenna element 118, and/or the like fordetermining whether the scanned RFID tags correspond to tag recordsstored in the first common memory unit 304 of the RFID reader 104. Ifthe scanned RFID tags correspond to duplicate entries of the tag recordsin the first common memory unit 304 of the RFID reader 104, the RFIDreader 104 returns to step 804 to scan other RFID tags that may bepresent in proximity of the RFID reader 104.

At step 808, the RFID reader 104 may include means such as the thirdprocessor 318 of the first RFID tag 110, the third communicationinterface 320, the second RFID reader unit 314, the first antennaelement 120, the second antenna element 118, and/or the like for storingdata associated with the scanned RFID tags in the first common memoryunit 304 of the RFID reader 104, when the scanned RFID tags do notcorrespond to the tag records stored in the first common memory unit 304of the RFID reader 104. In an embodiment, the data is timestamped andstored in the first common memory unit 304 of the RFID reader 104.

FIG. 9 illustrates a flowchart 900 to operate the first RFID reader 102in the dense reader mode (DRM), according to one or more embodimentsdescribed herein.

At step 902, the first RFID reader 102 may include means such as thefirst processor 202, the first communication interface 206, the firstRFID reader unit 208, the first antenna element 114, the second antennaelement 116, and/or the like for configuring the first RFID reader 102in the DRM mode. In an embodiment, as described in conjunction with FIG.5, the first RFID reader 102 may operate in the DRM mode to avoidcausing interference in the communication of other RFID readersoperating in the vicinity of the first RFID reader 102.

At step 904, the first RFID reader 102 may include means such as thefirst processor 202, the first communication interface 206, the firstRFID reader unit 208, the first antenna element 114, the second antennaelement 116, and/or the like for scanning for RFID tags, for example,the first RFID tag 110 of the RFID reader 104 and/or the one or moresecond RFID tags 112 in the vicinity of the first RFID reader 102.

At step 906, the first RFID reader 102 may include means such as thefirst processor 202, the first communication interface 206, the firstRFID reader unit 208, the first antenna element 114, the second antennaelement 116, and/or the like for determining whether a tag ID of thescanned RFID tags corresponds to a slave RFID tag ID. If the tag ID ofthe scanned RFID tag does not correspond to a slave RFID tag ID, thenthe tag ID is added to a scanned RFID tags list stored in the firstmemory unit 204 of the first RFID reader 102. In an embodiment, thescanned RFID tags list stores a list of second RFID tags 112 that arelocated in the vicinity of the first RFID reader 102. If the tag ID ofthe scanned RFID tag corresponds to a slave RFID tag ID, then theprocess proceeds to step 908.

At step 908, the first RFID reader 102 may include means such as thefirst processor 202, the first communication interface 206, the firstRFID reader unit 208, the first antenna element 114, the second antennaelement 116, and/or the like for identifying zone information associatedwith the scanned RFID tags. In an embodiment, the zone informationindicates a zone of the mesh topology associated with the first RFID tagof a corresponding RFID reader and/or the second RFID tag.

At step 910, the first RFID reader 102 may include means such as thefirst processor 202, the first communication interface 206, the firstRFID reader unit 208, the first antenna element 114, the second antennaelement 116, and/or the like for enabling an SPI interface of the firstRFID reader 102 to allow communication between different components ofthe first RFID reader 102, for example, the first processor 202, thefirst memory unit 204, the first communication interface 206, the firstRFID reader unit 208, the first noise cancellation unit 210, the firstpower source unit 212, the first antenna element 114, and/or the secondantenna element 116.

Once the SPI interface is enabled, at step 912, the first RFID reader102 may include means such as the first processor 202, the firstcommunication interface 206, the first RFID reader unit 208, the firstantenna element 114, the second antenna element 116, and/or the like forreading the tag records stored in the first memory unit 204 of the firstRFID reader 102.

At step 914, the first RFID reader 102 may include means such as thefirst processor 202, the first communication interface 206, the firstRFID reader unit 208, the first antenna element 114, the second antennaelement 116, and/or the like for determining whether the scanned RFIDtags correspond to tag records stored in the first memory unit 204 ofthe first RFID reader 102. If the scanned RFID tags correspond toduplicate entries of the tag records in the first memory unit 204 of thefirst RFID reader 102, the first RFID reader 102 proceeds to step 918 tosend tag information of the scanned RFID tags to the central server 106via the network 108 and scan other RFID tags that may be present inproximity of the first RFID reader 102.

At step 916, the first RFID reader 102 may include means such as thefirst processor 202, the first communication interface 206, the firstRFID reader unit 208, the first antenna element 114, the second antennaelement 116, and/or the like for storing the tag information associatedwith the scanned RFID tags in the first memory unit 204 of the firstRFID reader 102, when the scanned RFID tags do not correspond to the tagrecords stored in the first memory unit 204 of the first RFID reader102. In an embodiment, the data is timestamped and stored in the firstmemory unit 204 of the first RFID reader 102.

Referring back to FIG. 1, FIG. 2, and FIG. 3, it can be observed thatthe first RFID reader 102 corresponds to master RFID reader, while theRFID reader 104 corresponds to a slave RFID reader. Further, the RFIDreader 104 acts as a master RFID reader for the second RFID reader 134.Accordingly, the second RFID reader 134 corresponds to the slave RFIDreader. During deployment of the one or more RFID readers (e.g., 102,134, and 104) in the system environment 100, each of the one or moreRFID readers (e.g., 102, 134, and 104) may be configured to store a listof the RFID readers that are slave to the respective one or more RFIDreader (e.g., 102, 134, and 104). For example, the first RFID reader 102may include the list of the RFID readers comprising the RFID reader 104and the RFID reader 124. More particularly, the list of RFID readersincludes the RFID tag ID of the RFID readers (104, 124). Similarly, theRFID reader 104 includes the list of RFID readers comprising the RFIDtag ID for the RFID reader 134.

Such a network of the RFID readers may allow the first RFID reader 102to get data from the remaining RFID readers (e.g., 104, 134). Forexample, the first RFID reader 102 may receive the data from the RFIDreader 104 by interrogating the RFID tag 110 in the RFID reader 104. Thedata (received from the RFID reader 104) includes the data obtained fromthe one or more second RFID tags 122 and the RFID tag 126 of the secondRFID reader 134. The data further includes the data obtained by thesecond RFID reader 134 from the one or more second tags 142 and 144. Aperson having ordinary skills in the art would appreciate that the oneor more second RFID tags 112, 122, 142, and 144 may be installed on theone or more assets to tracked in the system environment 100.Additionally, a set of second RFID tags of the one or more second RFIDtags 112, 122, 142, and 144 may be installed on the proximity sensorsand one or more workers working the system environment 100. Theproximity sensor may correspond to motion sensor that may get activatedwhen motion of the one or more workers is detected. Such informationpertaining to the activation of the proximity sensor is stored in thecorrespond RFID tag. Accordingly, the first RFID reader 102, the RFIDreader 104, and the second RFID reader 134 may obtain the datapertaining to the tracking of the one or more workers within the systemenvironment 100 from set of second RFID tags of the one or more secondRFID tags 112, 122, 142, and 144 associated with the one or more workersand/or the proximity sensors. In some examples, the set of second tagsassociated with the one or more workers and/or the proximity sensor mayhave a string in the tag ID. For Example, the Tag ID of a second RFIDtag associated a worker includes a string “H1A”

For the purpose of brevity, hereinafter, interrogating the RFID tag inan RFID reader has been interchangeably referred to as interrogating theRFID reader.

Further, referring to FIG. 6, the RFID reader 104 receives the firstinterrogation command from the first RFID reader 102 during the firsttime interval. Additionally, the RFID reader 104 may be configured totransmit the second interrogation command to the one or more second RFIDtags 122 during the first time interval. Further, the RFID reader 104may be configured to transmit the third interrogation command to theRFID reader 134 during the second time interval. To this end, the RFIDreader 104 may be configured to alternate between transmission of thesecond interrogation command and the third interrogation command duringsubsequent time intervals. However, the scope of the disclosure is notlimited to the RFID reader 104 alternating between the transmission ofthe second interrogation command and the third interrogation command. Insome examples, the RFID reader 104 may be configured to transmit thesecond interrogation command to the one or more second RFID tags (122A,122 b, and 122C) during two subsequent time intervals (i.e., the firsttime interval and the second time interval). Thereafter, during thethird time interval, the RFID reader 104 may be configured to transmitthe third interrogation command. Similarly, the person having ordinaryskills in the art can derive other patterns of transmitting the secondinterrogation command and the third interrogation command duringdifferent time intervals.

As discussed, in some examples, the RFID reader 104 may include a singleantenna that is shared between the RFID tag 110 and the second RFIDreader unit 314. In such an embodiment, the second processor 302 may beconfigured to implement TDMA to enable the RFID tag 110 and the secondRFID reader unit 314 to use the common antenna element (e.g., the firstantenna element 120). To this end, the second processor 302 may receivethe first interrogation command during the first time interval. Further,during the first time interval, the second processor 302 may transmitthe response to the first interrogation command to the first RFID reader102. During the second time interval, the second processor 302 may beconfigured to transmit the second interrogation command to the one ormore second RFID tags (122A, 122B, and 122C). Further, during the secondtime interval, the second processor 302 may be configured to receive theresponse from the one or more second RFID tags (122A, 122B, and 122C).Additionally or alternatively, the second processor 302 may beconfigured to transmit the third interrogation command to the secondRFID reader 134 during the third time interval. More particularly, thesecond processor 302 may be configured to transmit the thirdinterrogation command to the RFID tag in the second RFID reader 134during the third time interval. Further, during the third time interval,the second processor 302 may be configured to receive the response fromthe second RFID reader 134.

In some examples, a duration of the first time interval, the second timeinterval, and the third time interval may be different. For example, theduration of the third time interval and the first time interval may begreater than the second time interval. Such variation in the duration ofthe first time interval, the second time interval, and the third timeinterval may be to accommodate reception/transmission of varied sizeddata to/from the RFID readers. For example, a size of the data to bereceived from the second RFID reader 134 may be greater than the size ofthe data to be received from the one or more second RFID tags (122A,122B, and 122C). Accordingly, the duration of the second time intervalmay be less than the duration of the third time interval.

A person having ordinary skills in the art would appreciate that scopeof the disclosure is not limited to the RFID reader 104 defining theTDMA slots for transmitting/receiving the data. Similar to the RFIDreader 104, the first RFID reader 102 and the second RFID reader 134 mayalso define the TDMA slots for the transmitting/receiving the data(e.g., the interrogation command and/or response of the interrogationcommand). In some examples, the TDMA slots may be defined during thedeployment of the first RFID reader 102, the second RFID readers 134,and the RFID reader 104 in the system environment 100.

FIG. 10 illustrates a schematic diagram 1000 of TDMA slots defined bythe RFID reader 104, according to one or more embodiments describedherein. The schematic diagram 1000 illustrates TDMA slots 1002 a, and1002 b. Referring to TDMA slots 1002 a, the first slot 1004 depicts thefirst time interval during which the RFID reader 104 receives the firstinterrogation command from the first RFID reader 102 (depicted by 1006)and the transmit the second interrogation command to the one or moresecond RFID tags 122 (depicted by 1008). As discussed, the RFID reader104 is able to perform the operation of receiving the firstinterrogation command and transmitting the second interrogation commandconcurrently since different antenna elements (i.e., the first antennaelement 120 and the second antenna element 118) are used totransmit/receive the respective commands. The second slot 1010corresponds to the second time interval during which the RFID reader 104is configured to transmit the third interrogation command to the secondRFID reader 134. It can be further observed that the time duration ofthe first time slot 1004 is same as the second time slot 1010.

Referring to the TDMA slot 1002 b, the first slot 1012 depicts the firsttime interval during which the RFID reader 104 receives the firstinterrogation command from the first RFID reader 102 (depicted by 1006).The second slot 1014 depicts the second time interval during which theRFID reader 104 transmits the second interrogation command to the one ormore second RFID tags 122 (depicted by 1008). The third slot 1016corresponds to the third time interval during which the RFID reader 104is configured to transmit the third interrogation command to the secondRFID reader 134. It can be further observed that the time duration ofthe first time slot 1012 and the third time slot 1016 is greater thanthe second time slot 1014. In some examples, the TDMA slots 1002 bcorresponds to the embodiment when the RFID reader 104 has a singleantenna that is shared between the RFID tag 110 and the second RFIDreader unit 314.

In an example embodiment, the system environment 100 may be utilized totrack workers during hazardous scenarios such as, but not limited to,fire scenarios. In such an embodiment, the central server 106 may beconnected to one or more sensors (not shown) throughout the systemenvironment 100. In some examples, the one or more sensors include oneor more of gas sensors, fire sensors, infra-red sensors, and/or thelike. The one or more sensors may be configured to monitor brewing ofhazardous scenarios (such as fire) in the system environment 100. In aninstance in which the one or more sensors detects the hazardousscenarios, the one or more sensors may be configured to transmit amessage to the central server 106. Thereafter, the central server 106may be configured to transmit emergency message to the RFID readers inthe system environment 100 to configure the RFID readers in the systemenvironment 100 in the emergency mode. One or more methods of operatingthe RFID readers in the emergency mode is described in conjunction withFIG. 11.

FIG. 11 illustrates a flowchart 1100 of a method for operating the RFIDreader 102, according to one or more embodiments illustrated herein.

At step 1102, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst communication interface 206, and/or the like, for receiving theemergency message from the central server 106. As discussed, theemergency message is indicative of the hazardous scenario within thesystem environment 100.

At step 1104, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst communication interface 206, and/or the like, for updating anemergency flag in the first memory unit 204. More particularly, thefirst processor 202 may be configured to set a value of the emergencyflag as “1”. In an example embodiment, the emergency flag may beindicative of reception of the emergency message from the central server106. For example, if the value of the emergency flag is “1”, the firstprocessor 202 may determine that the one or more sensors have detectedthe hazardous scenario in the system environment 100. However, if thevalue of the emergency flag is “0”, the first processor 202 maydetermine that operations in the system environment 100 are normal.

FIG. 12 illustrates a flowchart 1200 of a method for operating the RFIDreader 102, according to one or more embodiments illustrated herein.

At step 1202, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, and/orthe like, for checking whether the value of the emergency flag is “1”.As discussed, the value of the emergency flag as “1” may indicate thatthe hazardous scenario has occurred in the system environment 100. Ifthe first processor 202 determines that the value of the emergency flagis “1”, the first processor 202 may be configured to perform the step1212. However, if the first processor 202 determines that the value ofthe emergency flag is “0”, the first processor 202 may be configured toperform the step 1204.

At step 1204, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, and/orthe like, for modifying a mode of operation of the first RFID reader 102to a default mode. At step 1206, the first RFID reader 102 includesmeans such as, but not limited to, the first processor 202, the firstmemory unit 204, the first RFID reader unit 208 and/or the like, fortransmitting the first interrogation command to the RFID reader 104during the first time interval. In some examples, the first RFID readerunit 208 may be configured to transmit the first interrogation commandto the first RFID tag 110 in the RFID reader 104 of the one or more RFIDreaders 104 and 124 (included the in the list of RFID readers that areslave to the first RFID reader 102). More particularly, the first RFIDreader unit 208 may be configured to retrieve the list of the RFIDreaders, from the first memory device 204, that are slave to the firstRFID reader 102. Thereafter, the first RFID reader unit 208 may beconfigured to transmit the first interrogation command to the RFID tag110 in the RFID reader (e.g., the RFID reader 104) identified from thelist of RFID readers (that are slave to the first RFID reader 102).Further, during the first time interval, the first RFID reader unit 208may be configured to receive the response for the first interrogationcommand from the first RFID tag 110 in the RFID reader 104. The responseincludes the data received from the RFID reader 104. The data includesthe data stored in the first common memory unit 304 of the RFID reader104. The data stored in the first common memory unit 304 includes thedata that the RFID reader 104 obtained from the one or more second tags122 and the second RFID readers 136 and 134.

At 1208, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for writing the data,received in the response, to the first interrogation command to thefirst memory unit 204. As discussed, the data received from the firstRFID tag 110 in the RFID reader 104 includes the data received from theone or more second RFID tags 122 proximal to the RFID reader 104 and thedata further obtained from the respective slave RFID readers (i.e., thesecond RFID readers 134 and 136). Accordingly, the RFID reader 102 mayreceive the data from each RFID reader deployed in the systemenvironment 100.

At 1210, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for transmitting the secondinterrogation command to the one or more second RFID tags 112. In someexamples, the one or more second RFID tags 112 are positioned proximalto the first RFID reader 102. Further, during the second time interval,the first RFID reader unit 208 may be configured to receive the responsefrom the one or more second RFID tags 112 positioned proximal to thefirst RFID reader 102. Additionally, the first RFID reader unit 208 maybe configured to store the data received from the one or more secondRFID tags 112 into the first memory unit 204. Thereafter, the firstprocessor 202 may be configured to repeat the step 1202 for theremaining RFID readers in the list of RFID readers. In some examples,the scope of the disclosure is not limited to transmitting the firstinterrogation command and the second interrogation command at differentsteps (i.e., the step 1208 and 1210). In an example embodiment, thefirst RFID reader unit 208 may be configured to transmit the firstinterrogation command concurrent to the second interrogation commandusing the different antenna elements (i.e., the first antenna element114 and the second antenna element 116).

At step 1212, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for configuring the firstRFID reader 102 in the emergency mode. At step 1214, the first RFIDreader 102 includes means such as, but not limited to, the firstprocessor 202, the first memory unit 204, the first RFID reader unit 208and/or the like, for broadcasting the emergency message to each RFIDreader in the list of RFID readers (e.g., the RFID reader 104 and 124)that are slave to the first RFID reader 102. In some examples, the firstRFID reader unit 208 may be configured to utilize known protocols suchas, but not limited to, EPC protocols, to broadcast the emergencymessage to the RFID readers (e.g., the RFID readers 104 and 124).

For the purpose of ongoing description, it is assumed that the firstRFID reader unit 208 may be configured to receive the data from the RFIDreader 104 that further receives the data from the second RFID readers132 and 134. However, those having ordinary skills in the art wouldappreciate that the first RFID reader 102 may additionally receive thedata from the RFID reader 124 and/or the one or more second RFID readers138 and 140.

At step 1216, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for transmitting the firstinterrogation command to a RFID reader (e.g., the RFID reader 104) fromthe list of RFID readers that are slave to the first RFID reader 102during the first time interval. At step 1218, the first RFID reader 102includes means such as, but not limited to, the first processor 202, thefirst memory unit 204, the first RFID reader unit 208 and/or the like,for receiving the response to the first interrogation command from theRFID reader 104. As discussed, the response to the first interrogationcommand includes the data corresponding to the one or more second tags122 that are proximal to the RFID reader 104. Additionally, the dataincludes data that RFID reader 104 obtained from the second RFID readers134 and 136 (that are slave to the RFID reader 104). Since the datareceived for the second RFID readers 134 and 136 corresponds to the datathat the second RFID readers 134 and 136 obtained from the one or moresecond RFID tags 142 and 144 (that are proximal the second RFID reader134 and 136). Accordingly, the data received in response to the firstinterrogation command includes the data corresponding to the one or moresecond RFID tags 112, 122, 142, and 144. In some examples, the datareceived by the first RFID reader 102 from the other RFID readers (e.g.,104) may be indexed/flagged based on the RFID reader from which the datahas been received. Following table illustrates example data received bythe first RFID reader 102:

Data RFID reader Data-1 RFID reader 104 Data-2 Second RFID reader 134Data-3 Second RFID reader 136

At step 1220, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for determining whether thedata indicates activation of the proximity sensor and/or presence of theone or more workers. In some examples, the first RFID reader unit 208may be configured to identify presence of the predefined TAG ID in thedata to determine whether the data indicates the presence of the one ormore workers and/or activation of the proximity sensor. For example, ifthe data includes the tag ID “H1A”, the first RFID reader unit 208 maydetermine that the data received from the RFID reader 104 indicates thepresence of the one or more workers in the system environment 100. Insome examples, activation of the proximity sensor or presence of thedata obtained from the one or more second RFID tag associated with theone or more workers may indicate presence of workers in the systemenvironment 100 during hazardous scenario. If the first reader unit 208determines that the data indicates presence of the one or more workersand/or activation of the proximity sensor, the first reader unit 208 maybe configured to perform the step 1218. However, if the first readerunit 208 identifies that the data does not indicates the presence of theone or more workers and/or activation of the proximity sensor, the firstreader unit 208 may be configured to repeat the step 1216.

At step 1222, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for flagging the RFID reader104 and/or the one or more second RFID readers 134 and 136 from wherethe first RFID reader unit 208 received the data that indicates thepresence of the one or more workers and/or activation of the proximitysensor. Since the data received from the RFID reader 104 and/or the oneor more second RFID readers 134 and 136 is indexed based on the RFIDreader, the first RFID reader unit 208 is able to identify the RFIDreader(of the RFID reader 104 and/or the one or more second RFID readers134 and 136) that has sent the data indicating the presence of the oneor more workers.

Flagging the RFID reader 104 and/or the one or more second RFID readers134 and 136 may indicate the presence of the one or more worker withinthe proximity of the RFID reader 104 and/or the one or more second RFIDreaders 134 and 136. Additionally, the first RFID reader unit 208 may beconfigured to store the information pertaining to the flagged RFIDreaders in the first memory unit 204.

FIG. 13 illustrates another flowchart 1300 of a method for operating thefirst RFID reader 102, according to one or more embodiments illustratedherein.

At step 1302, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for identifying a flaggedRFID reader (e.g., RFID reader 104) from the information pertaining tothe flagged RFID readers. At step 1304, the first RFID reader 102includes means such as, but not limited to, the first processor 202, thefirst memory unit 204, the first RFID reader unit 208 and/or the like,for transmitting the first interrogation command to the RFID tag 110 ofthe RFID reader (e.g., the RFID reader 104) during the first timeinterval. At step 1306, the first RFID reader 102 includes means suchas, but not limited to, the first processor 202, the first memory unit204, the first RFID reader unit 208 and/or the like, for modifying theduration of the first time interval by a predefined time period. Forexample, the first reader unit 208 may be configured to increase thefirst time interval by 50 ms. In some examples, the step 1306 isoptional and the first RFID reader unit 208 may not modify the firsttime interval.

At step 1308, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for receiving the responsefor the first interrogation command from the RFID reader 104. Asdiscussed, the response for the first interrogation command includes thedata that the RFID reader 104 obtained from a set of second RFID tagsthat are associated with the one or more workers and/or proximitysensors. At step 1310, the first RFID reader 102 includes means such as,but not limited to, the first processor 202, the first memory unit 204,the first RFID reader unit 208 and/or the like, for checking whether thedata received from the RFID reader 104 indicates the presence of the oneor more workers and/or activation of the proximity sensor. If the firstRFID reader unit 208 determines that the data does not indicate thepresence of the one or more workers and/or activation of the proximitysensor, the first RFID reader unit 208 may be configured to perform thestep 1312. However, if the first reader unit 208 determines that thedata received from the RFID reader 104 indicates the presence of the oneor more workers and/or activation of the proximity sensor, the firstRFID reader unit 208 may be configured to perform the step 1314.

At step 1312, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for unflagging the RFIDreader 104. Thereafter, the first RFID reader unit 208 may be configuredto perform step 1316. At step 1314, the first RFID reader 102 includesmeans such as, but not limited to, the first processor 202, the firstmemory unit 204, the first RFID reader unit 208 and/or the like, forstoring the data pertaining to the one or more workers and/or activationof the proximity sensor in the first memory device 204.

At step 1316, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for checking whether eachflagged RFID reader has been interrogated. If the first RFID reader unit208 determines that the each of the flagged RFID reader has beeninterrogated, the first RFID reader unit 208 may be configured toperform the step 1318. However, if the first RFID reader unit 208determines that each of the flagged RFID reader has not beeninterrogated, the first RFID reader unit 208 may be configured to repeatthe step 1302.

At step 1318, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for transmitting the secondinterrogation command to each of the one or more second RFID tags 112.In some examples, the second interrogation command includes tag ID of aset of second RFID tags of the one or more second RFID tags 112. In anexample embodiment, the set of second RFID tags corresponds to the tagsassociated with the proximity sensor and/or the one or more workers. Forexample, the first RFID reader unit 208 may transmit the secondinterrogation command as “READ WHERE HEX=H1A”. Accordingly, the firstRFID reader unit 208 directs the second interrogation command to the setof second RFID tags having “H1A” in the tag ID.

At step 1320, the first RFID reader 102 includes means such as, but notlimited to, the first processor 202, the first memory unit 204, thefirst RFID reader unit 208 and/or the like, for checking whether thedata received from the set of second RFID tags indicates the presence ofthe one or more workers and/or activation of the proximity sensor. Insome examples, the first RFID reader unit 208 may determine the presenceof the one or more workers based on reception of the response from theset of second RFID tags. If the first RFID reader unit 208 does notreceive the response from the set of second RFID tags, the first RFIDreader unit 208 may determine that no worker is present in the proximityof the first RFID reader 102. However, if the first RFID reader unit 208does receive the response from the set of second RFID tags, the firstRFID reader unit 208 may determine that worker is present in theproximity of the first RFID reader 102. Accordingly, at step 1322, thefirst RFID reader unit 208 may be configured to write the data receivedfrom the second set of RFID tags in the first memory device 204. Else,the first RFID reader unit 208 may be configured to repeat the step1302.

In some examples, the central server 106 may be configured to read thedata from the first memory device 204 of the first RFID reader 102. Asthe data indicates the presence of the one or more workers in the systemenvironment 100, the central server 106 may be configured to utilize thedata to track the one or more workers.

In some examples, the method described in the FIG. 11-13 enable thefirst RFID reader unit 208 to the reassign the TDMA slot to interrogatethe flagged RFID readers. Accordingly, the first RFID reader 102prioritizes interrogation of the flagged RFID reader to track the one ormore workers through the system environment 100. For example, the firstRFID reader 102 transmits the first interrogation command during thesecond time interval for interrogating flagged RFID reader, which wasoriginally (i.e., in the default mode) used for transmitting the secondinterrogation command for interrogating the one or more second RFIDtags. In another example, the first RFID reader 102 transmits the firstinterrogation command during the third time interval for interrogatingflagged RFID reader, which was originally (i.e., in the default mode)used for transmitting the first interrogation command for interrogatingan unflagged RFID reader.

In an example embodiment, the RFID reader 104 may be configured tofollow similar methodology, as the first RFID reader 102, to operate inthe emergency mode. Further similar to the first RFID reader 102, theRFID reader 104 may reassign the TDMA slots to transmit the firstinterrogation command to the flagged RFID readers (e.g., the second RFIDreaders 134 and 136) that are slave to the RFID reader 104. On suchmethod of operating the RFID reader 104 in the emergency mode isdescribed in FIG. 14.

FIG. 14 illustrates a flowchart 1400 of a method for operating the RFIDreader 104 in the emergency mode, according to one or more embodimentsillustrated herein.

At step 1402, the RFID reader 104 includes means such as, the secondprocessor 302, the second communication interface unit 310, the secondRFID reader unit 314, and/or the like, for checking whether all theflagged second RFID readers (e.g., 134) have been interrogated. If thesecond RFID reader unit 314 determines that the all the flagged secondRFID readers (e.g., 134) have been interrogated, the second RFID readerunit 314 may be configured to perform the step 1412. However, if thesecond RFID reader unit 314 determines that not all the second flaggedRFID readers have been interrogated, the second RFID reader unit 314 maybe configured to perform the step 1404.

At step 1404, the RFID reader 104 includes means such as, the secondprocessor 302, the second communication interface unit 310, the secondRFID reader unit 314, and/or the like, for transmitting the secondinterrogation command to the flagged second RFID readers (e.g., thesecond RFID reader 134), during the first time interval. At step 1406,the RFID reader 104 includes means such as, the second processor 302,the second communication interface unit 310, the second RFID reader unit314, and/or the like, for receiving the response to the secondinterrogation command from the flagged second RFID readers (e.g., thesecond RFID reader 134), during the first time interval. In an exampleembodiment, the response to the second interrogation command includesthe data that the second RFID reader 134 may have obtained from the setof second RFID tag (e.g., 142). At step 1408, the RFID reader 104includes means such as, the second processor 302, the secondcommunication interface unit 310, the second RFID reader unit 314,and/or the like, for checking whether the data received from the secondRFID reader 104 indicates the presence of the worker within the systemenvironment 100. For example, the second RFID reader unit 314 maydetermine whether the data includes tag ID associated with the one ormore workers. If the second RFID reader unit 314 determines that thedata includes the tag ID of the one or more workers, the second RFIDreader unit 314 may be configured to determine that the data indicatesthe presence of the one or more workers. Additionally or alternatively,if the second RFID reader unit 314 may determine that the data indicatesthat the proximity sensor is activated, the second RFID reader unit 314may determine that the data indicates the presence of the one or moreworkers in the system environment 100. Accordingly, the second RFIDreader unit 314 may perform the step 1410. However, if the second RFIDreader unit 314 determines that the data does not indicate the presenceof the one or more workers in the system environment 100, the secondRFID reader unit 314 may be configured to repeat the step 1402

At step 1410, the RFID reader 104 includes means such as, the secondprocessor 302, the second communication interface unit 310, the secondRFID reader unit 314, and/or the like, for writing the data in the firstcommon memory unit 304. Thereafter, the second RFID reader unit 314 maybe configured to repeat the step 1402.

At step 1412, the RFID reader 104 includes means such as, the secondprocessor 302, the second communication interface unit 310, the secondRFID reader unit 314, and/or the like, for transmitting the thirdinterrogation command to the set of the second RFID tags 122, as isdescribed in the step 1318. At step 1414, the RFID reader 104 includesmeans such as, the second processor 302, the second communicationinterface unit 310, the second RFID reader unit 314, and/or the like,for checking whether the data received from the set of second RFID tagsindicates the presence of the one or more workers and/or activation ofthe proximity sensor. In some examples, the second RFID reader unit 314may determine the presence of the one or more workers based on receptionof the response from the set of second RFID tags. If the second RFIDreader unit 314 does not receive the response from the set of secondRFID tags, the second RFID reader unit 314 may determine that no workeris present in the proximity of the first RFID reader 102. However, ifthe second RFID reader unit 314 does receive the response from the setof second RFID tags, the second RFID reader unit 314 may determine thatworker is present in the proximity of the first RFID reader 102.

If the second RFID reader unit 314 determines that the data receivedfrom the set of second RFID tag does not indicate the presence of theone or more workers, the second RFID reader unit 314 may be configuredto repeat the step 1402. If the second RFID reader unit 314 determinesthat the data received from the set of second RFID tag indicates thepresence of the one or more workers, the second RFID reader unit 314 maybe configured to perform the step 1416. At step 1416, the RFID reader104 includes means such as, the second processor 302, the secondcommunication interface unit 310, the second RFID reader unit 314,and/or the like, for writing the data received from the set of secondRFID tags in the first common memory unit 304.

Accordingly, from FIG. 14 it can be observed that in the emergency mode,the RFID reader 104 reassign the time interval to interrogate theflagged second RFID readers 134.

FIG. 15 illustrates an example scenario 1500 depicting the communicationamongst the first RFID reader 102, the RFID reader 104, and the one ormore second RFID readers 134 and 136, according to one or moreembodiments illustrated herein.

Referring to the example scenario 1500, the first RFID reader 102utilizes the first time interval to transmit the first interrogationcommand to the RFID reader 104. During the first time interval, thefirst RFID reader 102 receives the response from the RFID reader 104.Further, the first RFID reader 102 utilizes the second time interval totransmit the second interrogation command to the one or more second RFIDtags 112. During the second time interval, the first RFID reader 102receives the response from the one or more second RFID tags 112.Thereafter, the first RFID reader 102 may be configured to repeat theaforementioned method to interrogate the RFID reader 102 and the one ormore second RFID tags 112.

The TDMA slots 1502 depicts the first time interval and the second timeinterval that the first RFID reader 102 utilizes to transmit the firstinterrogation command and the second interrogation command. Further, theTDMA slots 1502 depicts the third time interval and the fourth timeinterval that is utilized to repeat the transmission of the firstinterrogation command and the second interrogation command.

Further, the example scenario 1500 illustrates that the RFID reader 104transmits the second interrogation command to the second RFID reader 134during the first time interval. Additionally, the RFID reader 104 maytransmit the third interrogation command to the one or more second RFIDtags 122 during the second time interval. Thereafter, the RFID reader104 may be configured to repeat the aforementioned process in subsequenttime intervals for interrogating the second RFID reader 136 and the oneor more second RFID tags 122.

The TDMA slots 1504 depicts the first time interval and the second timeinterval that the RFID reader 104 utilizes to transmit the secondinterrogation command (to the second RFID reader 134) and the thirdinterrogation command to the one or more second RFID tags 112. Further,the TDMA slots 1504 depicts the third time interval and the fourth timeinterval that the RFID reader 104 utilizes to transmit the secondinterrogation command to the second RFID reader 136, and the thirdinterrogation command to the one or more second RFID tags 112.

FIG. 16 illustrates an example scenario 1600 depicting the communicationamongst the first RFID reader 102, the RFID reader 104, and the one ormore second RFID readers 134 and 136, during the hazardous scenario,according to one or more embodiments illustrated herein.

It can be observed that the RFID reader 104 and the second RFID readers134 and 136 have been flagged. Referring to the example scenario 1600,the first RFID reader 102 utilizes the first time interval to transmitthe first interrogation command to the RFID reader 104. During the firsttime interval, the first RFID reader 102 receives the response from theRFID reader 104. Further, the first RFID reader 102 utilizes the secondtime interval to transmit the second interrogation command to the one ormore second RFID tags 112. During the second time interval, the firstRFID reader 102 receives the response from the one or more second RFIDtags 112. Thereafter, the first RFID reader 102 may be configured torepeat the aforementioned method to interrogate the RFID reader 102 andthe one or more second RFID tags 112.

The TDMA slots 1602 depicts the first time interval and the second timeinterval that the first RFID reader 102 utilizes to transmit the firstinterrogation command and the second interrogation command. Further, theTDMA slots 1602 depicts the third time interval and the fourth timeinterval that is utilized to repeat the transmission of the firstinterrogation command and the second interrogation command.

Further, the example scenario 1600 illustrates that the RFID reader 104transmits the second interrogation command to the second RFID reader 134during the first time interval. Additionally, the RFID reader 104 maytransmit the second interrogation command to the second RFID reader 136during the second time interval. It can be observed that the second timeinterval is not being used to interrogated the flagged RFID readerinstead of the one or more second RFID tags 112. Thereafter, the RFIDreader 104 may be configured to transmit the third interrogation commandto the one or more second RFID tags 112 during the third time interval.

The TDMA slots 1604 depicts the first time interval and the second timeinterval that the RFID reader 104 utilizes to transmit the secondinterrogation command (to the second RFID reader 134), and the secondinterrogation command to the second RFID reader 136. Further, it can beobserved that the RFID reader 104 may be configured to transmit thethird interrogation command during the third time interval.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flow charts,schematics, exemplary, and examples. Insofar as such block diagrams,flow charts, schematics, and examples contain one or more functionsand/or operations, each function and/or operation within such blockdiagrams, flowcharts, schematics, or examples can be implemented,individually and/or collectively, by a wide range of hardware thereof.

It is noted that each block of the flowchart, and combinations of blocksin the flowchart, may be implemented by various means such as hardware,firmware, circuitry and/or other devices associated with execution ofsoftware including one or more computer program instructions. Forexample, one or more of the procedures described above may be embodiedby computer program instructions, which may be stored by anon-transitory memory of an apparatus employing an embodiment of thepresent disclosure and executed by a processor in the apparatus. Thesecomputer program instructions may direct a computer or otherprogrammable apparatus to function in a particular manner, such that theinstructions stored in the computer-readable storage memory produce anarticle of manufacture, the execution of which implements the functionspecified in the flowchart block(s).

Embodiments of the present disclosure may be configured as methods,mobile devices, backend network devices, and the like. Accordingly,embodiments may comprise various means including entirely of hardware orany combination of software and hardware. Furthermore, embodiments maytake the form of a computer program product on at least onenon-transitory computer-readable storage medium having computer-readableprogram instructions (e.g., computer software) embodied in the storagemedium. Similarly, embodiments may take the form of a computer programcode stored on at least one non-transitory computer-readable storagemedium. Any suitable computer-readable storage medium may be utilizedincluding non-transitory hard disks, CD-ROMs, flash memory, opticalstorage devices, or magnetic storage devices.

In one embodiment, examples of the present disclosure may be implementedvia Application Specific Integrated Circuits (ASICs). However, theembodiments disclosed herein, in whole or in part, can be equivalentlyimplemented in standard integrated circuits, as one or more computerprograms running on one or more computers (e.g., as one or more programsrunning on one or more computer systems), as one or more programsrunning on one or more processing circuitries (e.g., micro-processingcircuitries), as one or more programs running on one or more processors(e.g., microprocessors), as firmware, or as virtually any combinationthereof.

In addition, those skilled in the art will appreciate that examplemechanisms disclosed herein may be capable of being distributed as aprogram product in a variety of tangible forms, and that an illustrativeembodiment applies equally regardless of the particular type of tangibleinstruction bearing media used to actually carry out the distribution.Examples of tangible instruction bearing media include, but are notlimited to, the following: recordable type media such as floppy disks,hard disk drives, CD ROMs, digital tape, flash drives, and computermemory.

What is claimed is:
 1. A radio-frequency identification (RFID) readercomprising: a first RFID tag comprising a first antenna elementconfigured to operate at a first transmit power, wherein the first RFIDtag is configured to: receive, in a first time interval, a firstinterrogation command from a first RFID reader through the first antennaelement; and in response to receiving the first interrogation command,transmit, in the first time interval, a first response signal to thefirst RFID reader; a second antenna element configured to operate at asecond transmit power that is below the first transmit power of thefirst antenna element; and a processor communicatively coupled to thesecond antenna element, wherein the processor is configured to transmit,in the first time interval, a second interrogation command to one ormore second RFID tags through the second antenna element.
 2. The RFIDreader of claim 1, wherein the RFID reader is configured to operate in adense reader mode to avoid interference with another RFID readersimultaneously transmitting, in the first time interval, the secondinterrogation command to the one or more second RFID tags.
 3. The RFIDreader of claim 1, wherein the first RFID tag is configured to:transmit, in a second time interval, a third interrogation command to afirst RFID tag of a second RFID reader through the first antenna elementoperating at the first transmit power, wherein the second time intervaloccurs subsequent to the first time interval; and receive, in the secondtime interval, a third response signal from the second RFID reader. 4.The RFID reader of claim 3, wherein the first RFID tag of the RFIDreader is configured to operate in a dense reader mode to avoidinterference with a first RFID tag of another RFID reader simultaneouslytransmitting the third interrogation command to the first RFID tag ofthe second RFID reader.
 5. The RFID reader of claim 1, wherein theprocessor is further configured to: receive a second response signalfrom the one or more second RFID tags in the first time interval throughthe second antenna element, in response to transmitting the secondinterrogation command; and timestamp and store data received in thesecond response signal in a memory unit shared between the processor andthe first RFID tag.
 6. The RFID reader of claim 1, wherein the firstRFID reader corresponds to a master RFID reader that is configured to becoupled to a central server via a network, and wherein the first RFIDreader is configured to transmit data received in the first responsesignal to the central server via the network.
 7. The RFID reader ofclaim 1, wherein the first RFID reader corresponds to a slave RFIDreader that is configured to relay data received in the first responsesignal to a master RFID reader preceding the first RFID reader or torelay the data received in the first response signal to the master RFIDreader through one or more preceding slave RFID readers coupled betweenthe master RFID reader and the first RFID reader.
 8. The RFID reader ofclaim 1, further comprising a noise cancellation unit that is configuredto remove interference between the reception of the first interrogationcommand and the transmission of the second interrogation command.
 9. TheRFID reader of claim 1, wherein, in response to the first interrogationcommand, the first RFID tag is further configured to interrupt a memoryunit shared with the processor to retrieve data in accordance with afirst protocol.
 10. The RFID reader of claim 9, wherein the first RFIDtag is further configured to transform the retrieved data in accordancewith a second protocol, wherein the second protocol is utilized totransmit the first response signal to the first RFID reader, and whereinthe first response signal comprises the transformed data.
 11. A methodcomprising: receiving, by a first RFID tag of an RFID reader, through afirst antenna element of the RFID reader in a first time interval, afirst interrogation command from a first RFID reader, wherein the firstantenna element is configured to operate at a first transmit power;transmitting, by the first RFID tag, in the first time interval, a firstresponse signal to the first RFID reader, in response to receiving thefirst interrogation command; and transmitting, by a processor of theRFID reader, in the first time interval, a second interrogation commandto one or more second RFID tags through a second antenna element of theRFID reader, wherein the second antenna element is configured to operateat a second transmit power that is below the first transmit power of thefirst antenna element.
 12. The method of claim 11, further comprising,causing, by the processor of the RFID reader, to operate the RFID readerin a dense reader mode to avoid interference with another RFID readersimultaneously transmitting, in the first time interval, the secondinterrogation command to the one or more second RFID tags.
 13. Themethod of claim 11, further comprising: transmitting, by the first RFIDtag, in a second time interval, a third interrogation command to a firstRFID tag of a second RFID reader through the first antenna elementoperating at the first transmit power, wherein the second time intervaloccurs subsequent to the first time interval; and receiving, by thefirst RFID tag, in the second time interval, a third response signalfrom the second RFID reader.
 14. The method of claim 13, furthercomprising, operating the first RFID tag of the RFID reader in a densereader mode to avoid interference with a first RFID tag of another RFIDreader simultaneously transmitting the third interrogation command tothe first RFID tag of the second RFID reader.
 15. The method of claim11, further comprising: receiving, by the processor of the RFID reader,a second response signal from the one or more second RFID tags in thefirst time interval through the second antenna element, in response totransmitting the second interrogation command; and timestamping andstoring, by the processor of the RFID reader, data received in thesecond response signal in a memory unit shared between the processor andthe first RFID tag.
 16. The method of claim 11, wherein the first RFIDreader corresponds to a master RFID reader that is configured to becoupled to a central server via a network, and further comprisingrelaying, by the first RFID tag of the RFID reader, data in the firstresponse signal to the central server through the first RFID reader. 17.The method of claim 11, wherein the first RFID reader corresponds to aslave RFID reader that is configured to relay data received in the firstresponse signal to a master RFID reader preceding the first RFID readeror to relay the data received in the first response signal to the masterRFID reader through one or more preceding slave RFID readers coupledbetween the master RFID reader and the first RFID reader.
 18. The methodof claim 11, further comprising removing interference between thereception of the first interrogation command and the transmission of thesecond interrogation command.
 19. The method of claim 11, furthercomprising interrupting, by the first RFID tag, a memory unit sharedwith the processor of the RFID reader, to retrieve data in accordancewith a first protocol in response to the first interrogation command.20. The method of claim 19, further comprising, transforming, by thefirst RFID tag, the retrieved data in accordance with a second protocol,wherein the second protocol is utilized to transmit the first responsesignal to the first RFID reader, and wherein the first response signalcomprises the transformed data.